Full List of INPUT Keywords

Full List of INPUT Keywords#

Full List of INPUT Keywords

System variables#

These variables are used to control general system parameters.

suffix#

Type: String
Description: In each run, ABACUS will generate a subdirectory in the working directory. This subdirectory contains all the information of the run. The subdirectory name has the format: OUT.suffix, where the suffix is the name you can pick up for your convenience.
Default: ABACUS

calculation#

Type: String
Description: Specify the type of calculation.
- scf: perform self-consistent electronic structure calculations
- nscf: perform non-self-consistent electronic structure calculations. A charge density file is required
- relax: perform structure relaxation calculations, the relax_nmax parameter depicts the maximal number of ionic iterations
- cell-relax: perform cell relaxation calculations
- md: perform molecular dynamics simulations
- get_pchg: obtain partial (band-decomposed) charge densities (for LCAO basis only). See nbands_istate and bands_to_print for more information
- get_wf: obtain wave functions (for LCAO basis only). See nbands_istate and bands_to_print for more information
- get_S : obtain the overlap matrix formed by localized orbitals (for LCAO basis with multiple k points). the file name is SR.csr with file format being the same as that generated by out_mat_hs2
- gen_bessel : generates projectors, i.e., a series of Bessel functions, for the DeePKS method (for LCAO basis only); see also keywords bessel_descriptor_lmax, bessel_descriptor_rcut and bessel_descriptor_tolerence. A file named jle.orb will be generated which contains the projectors. An example is provided in examples/H2O-deepks-pw
- test_memory : obtain a rough estimation of memory consuption for the calculation
- test_neighbour : obtain information of neighboring atoms (for LCAO basis only), please specify a positive search_radius manually
Default: scf

esolver_type#

Type: String
Description: choose the energy solver.
- ksdft: Kohn-Sham density functional theory
- ofdft: orbital-free density functional theory
- sdft: stochastic density functional theory
- tddft: real-time time-dependent density functional theory (TDDFT)
- lj: Leonard Jones potential
- dp: DeeP potential, see details in md.md
- ks-lr: Kohn-Sham density functional theory + LR-TDDFT
- lr: LR-TDDFT with given KS orbitals
Default: ksdft

symmetry#

Type: Integer
Description: takes value 1, 0 or -1.
- -1: No symmetry will be considered. It is recommended to set -1 for non-colinear + soc calculations, where time reversal symmetry is broken sometimes.
- 0: Only time reversal symmetry would be considered in symmetry operations, which implied k point and -k point would be treated as a single k point with twice the weight.
- 1: Symmetry analysis will be performed to determine the type of Bravais lattice and associated symmetry operations. (point groups, space groups, primitive cells, and irreducible k-points)
Default:
- 0:
  - if calculation==md/nscf/get_pchg/get_wf/get_S or gamma_only==True;
  - If (dft_fuctional==hse/hf/pbe0/scan0/opt_orb or rpa==True). Currently symmetry==1 is not supported in EXX (exact exchange) calculation.
  - If efield_flag==1
- 1: else

symmetry_prec#

Type: Real
Description: The accuracy for symmetry judgment. Usually the default value is good enough, but if the lattice parameters or atom positions in STRU file is not accurate enough, this value should be enlarged.

Note: if calculation==cell_relax, this value can be dynamically changed corresponding to the variation of accuracy of the lattice parameters and atom positions during the relaxation. The new value will be printed in OUT.${suffix}/running_cell-relax.log in that case.
Default: 1.0e-6
Unit: Bohr

symmetry_autoclose#

Type: Boolean
Availability: symmetry==1
Description: Control how to deal with error in symmetry analysis due to inaccurate lattice parameters or atom positions in STRU file, especially useful when calculation==cell-relax
- False: quit with an error message
- True: automatically set symmetry to 0 and continue running without symmetry analysis
Default: True

kpar#

Type: Integer
Description: divide all processors into kpar groups, and k points will be distributed among each group. The value taken should be less than or equal to the number of k points as well as the number of MPI processes.
Default: 1

bndpar#

Type: Integer
Description: divide all processors into bndpar groups, and bands (only stochastic orbitals now) will be distributed among each group. It should be larger than 0.
Default: 1

latname#

Type: String
Description: Specifies the type of Bravias lattice. When set to none, the three lattice vectors are supplied explicitly in STRU file. When set to a certain Bravais lattice type, there is no need to provide lattice vector, but a few lattice parameters might be required. For more information regarding this parameter, consult the page on STRU file.

Available options are (correspondence with ibrav in QE(Quantum Espresso) is given in parenthesis):
- none: free structure
- sc: simple cubic (1)
- fcc: face-centered cubic (2)
- bcc: body-centered cubic (3)
- hexagonal: hexagonal (4)
- trigonal: trigonal (5)
- st: simple tetragonal (6)
- bct: body-centered tetragonal (7)
- so: orthorhombic (8)
- baco: base-centered orthorhombic (9)
- fco: face-centered orthorhombic (10)
- bco: body-centered orthorhombic (11)
- sm: simple monoclinic (12)
- bacm: base-centered monoclinic (13)
- triclinic: triclinic (14)
Default: none

psi_initializer#

Type: Integer
Description: enable the experimental feature psi_initializer, to support use numerical atomic orbitals initialize wavefunction (basis_type pw case).

NOTE: this feature is not well-implemented for nspin 4 case (closed presently), and cannot use with calculation nscf/esolver_type sdft cases. Available options are:
- 0: disable psi_initializer
- 1: enable psi_initializer
Default: 0

init_wfc#

Type: String
Description: Only useful for plane wave basis only now. It is the name of the starting wave functions. In the future. we should also make this variable available for localized orbitals set.

Available options are:
- atomic: from atomic pseudo wave functions. If they are not enough, other wave functions are initialized with random numbers.
- atomic+random: add small random numbers on atomic pseudo-wavefunctions
- file: from binary files WAVEFUNC*.dat, which are output by setting out_wfc_pw to 2.
- random: random numbers
with psi_initializer 1, two more options are supported:
- nao: from numerical atomic orbitals. If they are not enough, other wave functions are initialized with random numbers.
- nao+random: add small random numbers on numerical atomic orbitals
Default: atomic

init_chg#

Type: String
Description: This variable is used for both plane wave set and localized orbitals set. It indicates the type of starting density.
- atomic: the density is starting from the summation of the atomic density of single atoms.
- file: the density will be read in from a binary file charge-density.dat first. If it does not exist, the charge density will be read in from cube files. Besides, when you do nspin=1 calculation, you only need the density file SPIN1_CHG.cube. However, if you do nspin=2 calculation, you also need the density file SPIN2_CHG.cube. The density file should be output with these names if you set out_chg = 1 in INPUT file.
- wfc: the density will be calculated by wavefunctions and occupations. Wavefunctions are read in from binary files WAVEFUNC*.dat while occupations are read in from file istate.info.
- auto: Abacus first attempts to read the density from a file; if not found, it defaults to using atomic density.
Default: atomic

init_vel#

Type: Boolean
Description:
- True: read the atom velocity (atomic unit : 1 a.u. = 21.877 Angstrom/fs) from the atom file (STRU) and determine the initial temperature md_tfirst. If md_tfirst is unset or less than zero, init_vel is autoset to be true.
- False: assign value to atom velocity using Gaussian distributed random numbers.
Default: False

mem_saver#

Type: Boolean
Description: Used only for nscf calculations.
- 0: no memory saving techniques are used.
- 1: a memory saving technique will be used for many k point calculations.
Default: 0

diago_proc#

Type: Integer
Availability: pw base
Description:
- 0: it will be set to the number of MPI processes. Normally, it is fine just leave it to the default value.
- >0: it specifies the number of processes used for carrying out diagonalization. Must be less than or equal to total number of MPI processes. Also, when cg diagonalization is used, diago_proc must be the same as the total number of MPI processes.
Default: 0

nbspline#

Type: Integer
Description: If set to a natural number, a Cardinal B-spline interpolation will be used to calculate Structure Factor. nbspline represents the order of B-spline basis and a larger one can get more accurate results but cost more. It is turned off by default.
Default: -1

kspacing#

Type: Real
Description: Set the smallest allowed spacing between k points, unit in 1/bohr. It should be larger than 0.0, and suggest smaller than 0.25. When you have set this value > 0.0, then the KPT file is unnecessary, and the number of K points nk_i = max(1, int(|b_i|/KSPACING_i)+1), where b_i is the reciprocal lattice vector. The default value 0.0 means that ABACUS will read the applied KPT file. If only one value is set (such as kspacing 0.5), then kspacing values of a/b/c direction are all set to it; and one can also set 3 values to set the kspacing value for a/b/c direction separately (such as: kspacing 0.5 0.6 0.7).

Note: if gamma_only is set to be true, kspacing is invalid.
Default: 0.0

min_dist_coef#

Type: Real
Description: a factor related to the allowed minimum distance between two atoms. At the beginning, ABACUS will check the structure, and if the distance of two atoms is shorter than min_dist_coef*(standard covalent bond length), we think this structure is unreasonable. If you want to calculate some structures in extreme conditions like high pressure, you should set this parameter as a smaller value or even 0.
Default: 0.2

device#

Type: String
Description: Specifies the computing device for ABACUS.

Available options are:
- cpu: for CPUs via Intel, AMD, or Other supported CPU devices
- gpu: for GPUs via CUDA or ROCm.
Known limitations: ks_solver must also be set to the algorithms supported. lcao_in_pw currently does not support gpu.
Default: cpu

precision#

Type: String
Description: Specifies the precision of the PW_SCF calculation.

Available options are:
- single: single precision
- double: double precision
Known limitations:
- pw basis: required by the single precision options
- cg/bpcg/dav ks_solver: required by the single precision options
Default: double

Plane wave related variables#

These variables are used to control the plane wave related parameters.

ecutwfc#

Type: Real
Description: Energy cutoff for plane wave functions, the unit is Rydberg. Note that even for localized orbitals basis, you still need to setup an energy cutoff for this system. Because our local pseudopotential parts and the related force are calculated from plane wave basis set, etc. Also, because our orbitals are generated by matching localized orbitals to a chosen set of wave functions from a certain energy cutoff, this set of localize orbitals is most accurate under this same plane wave energy cutoff.
Default: 50 Ry (PW basis), 100 Ry (LCAO basis)

ecutrho#

Type: Real
Description: Energy cutoff for charge density and potential, the unit is Rydberg. For norm-conserving pseudopotential you should stick to the default value, you can reduce it by a little but it will introduce noise especially on forces and stress. For ultrasoft pseudopotential a larger value than the default is often desirable (ecutrho = 8 to 12 times ecutwfc, typically). The use of gradient-corrected functional, especially in cells with vacuum, or for pseudopotential without non-linear core correction, usually requires an higher values of ecutrho to be accurately converged.
Default: 4*ecutwfc

nx, ny, nz#

Type: Integer
Description: If set to a positive number, then the three variables specify the numbers of FFT grid points in x, y, z directions, respectively. If set to 0, the number will be calculated from ecutrho.

Note: You must specify all three dimensions for this setting to be used.
Default: 0

ndx, ndy, ndz#

Type: Integer
Description: If set to a positive number, then the three variables specify the numbers of FFT grid (for the dense part of charge density in ultrasoft pseudopotential) points in x, y, z directions, respectively. If set to 0, the number will be calculated from ecutwfc.

Note: You must specify all three dimensions for this setting to be used.

Note: These parameters must be used combined with nx,ny,nz. If nx,ny,nz are unset, ndx,ndy,ndz are used as nx,ny,nz.
Default: 0

pw_seed#

Type: Integer
Description: Only useful for plane wave basis only now. It is the random seed to initialize wave functions. Only positive integers are available.
Default:0

pw_diag_thr#

Type: Real
Description: Only used when you use ks_solver = cg/dav/dav_subspace/bpcg. It indicates the threshold for the first electronic iteration, from the second iteration the pw_diag_thr will be updated automatically. For nscf calculations with planewave basis set, pw_diag_thr should be <= 1e-3.
Default: 0.01

pw_diag_nmax#

Type: Integer
Description: Only useful when you use ks_solver = cg/dav/dav_subspace/bpcg. It indicates the maximal iteration number for cg/david/dav_subspace/bpcg method.
Default: 40

pw_diag_ndim#

Type: Integer
Description: Only useful when you use ks_solver = dav or ks_solver = dav_subspace. It indicates dimension of workspace(number of wavefunction packets, at least 2 needed) for the Davidson method. A larger value may yield a smaller number of iterations in the algorithm but uses more memory and more CPU time in subspace diagonalization.
Default: 4

erf_ecut#

Type: Real
Description: Used in variable-cell molecular dynamics (or in stress calculation). See erf_sigma in detail.
Default: 0.0
Unit: Ry

fft_mode#

Type: Integer
Description: Set the mode of FFTW.
- 0: FFTW_ESTIMATE
- 1: FFTW_MEASURE
- 2: FFTW_PATIENT
- 3: FFTW_EXHAUSTIVE
Default: 0

erf_height#

Type: Real
Description: Used in variable-cell molecular dynamics (or in stress calculation). See erf_sigma in detail.
Default: 0.0
Unit: Ry

erf_sigma#

Type: Real
Description: In order to recover the accuracy of a constant energy cutoff calculation, the kinetic functional is modified, which is used in variable-cell molecular dynamics (or in stress calculation).

erf_ecut is the value of the constant energy cutoff; erf_height and erf_sigma are the height and the width of the energy step for reciprocal vectors whose square modulus is greater than erf_ecut. In the kinetic energy, G^2 is replaced by G^2 + erf_height * (1 + erf ( (G^2 - erf_ecut)/erf_sigma) )

See: M. Bernasconi et al., J. Phys. Chem. Solids 56, 501 (1995), doi:10.1016/0022-3697(94)00228-2
Default: 0.1
Unit: Ry

Numerical atomic orbitals related variables#

These variables are used to control the numerical atomic orbitals related parameters.

nb2d#

Type: Integer
Description: In LCAO calculations, we arrange the total number of processors in an 2D array, so that we can partition the wavefunction matrix (number of bands*total size of atomic orbital basis) and distribute them in this 2D array. When the system is large, we group processors into sizes of nb2d, so that multiple processors take care of one row block (a group of atomic orbitals) in the wavefunction matrix. If set to 0, nb2d will be automatically set in the program according to the size of atomic orbital basis:
- if size <= 500 : nb2d = 1
- if 500 < size <= 1000 : nb2d = 32
- if size > 1000 : nb2d = 64;
Default: 0

lmaxmax#

Type: Integer
Description: If not equals to 2, then the maximum l channels on LCAO is set to lmaxmax. If 2, then the number of l channels will be read from the LCAO data sets. Normally no input should be supplied for this variable so that it is kept as its default.
Default: 2.

lcao_ecut#

Type: Real
Description: Energy cutoff (in Ry) for two-center integrals in LCAO. The two-center integration table are obtained via a k space integral whose upper limit is about sqrt(lcao_ecut).
Default: ecutwfc

lcao_dk#

Type: Real
Description: k spacing (in Bohr${}^{-1}$) for two-center integrals. The two-center integration table are obtained via a k space integral on a uniform grid with spacing lcao_dk.
Default: 0.01

lcao_dr#

Type: Real
Description: r spacing (in Bohr) of the integration table of two-center integrals.
Default: 0.01

lcao_rmax#

Type: Real
Description: Maximum distance (in Bohr) for the two-center integration table.
Default: 30

search_radius#

Type: Real
Description: Searching radius in finding the neighbouring atoms. By default the radius will be automatically determined by the cutoffs of orbitals and nonlocal beta projectors.
Default: -1
Unit: Bohr

search_pbc#

Type: Boolean
Description: If True, periodic images will be included in searching for the neighbouring atoms. If False, periodic images will be ignored.
Default: True

bx, by, bz#

Type: Integer
Description: In the matrix operation of grid integral, bx/by/bz grids (in x, y, z directions) are treated as a whole as a matrix element. A different value will affect the calculation speed. The default is 0, which means abacus will automatically calculate these values.
Default: 0

elpa_num_thread#

Type: int
Description: Number of threads used in one elpa calculation.

If the number is below 0 or 0 or beyond the max number of threads, all elpa calculation will be using all mpi threads
Default: -1

num_stream#

Type :int
Description: choose the number of streams in GPU when we compute the LCAO. According to different devices , we may have different effects.For most devices,the stream is enough when the number is bigger then 2.
Default : “4”

Electronic structure#

These variables are used to control the electronic structure and geometry relaxation calculations.

basis_type#

Type: String
Description: Choose the basis set.
- pw: Using plane-wave basis set only.
- lcao: Using localized atomic orbital sets.
- lcao_in_pw: Expand the localized atomic set in plane-wave basis, non-self-consistent field calculation not tested.
Default: pw

ks_solver#

Type: String
Description: Choose the diagonalization methods for the Hamiltonian matrix expanded in a certain basis set.

For plane-wave basis,
- cg: cg method.
- bpcg: bpcg method, which is a block-parallel Conjugate Gradient (CG) method, typically exhibits higher acceleration in a GPU environment.
- dav: the Davidson algorithm.
- dav_subspace: Davidson algorithm without orthogonalization operation, this method is the most recommended for efficiency. pw_diag_ndim can be set to 2 for this method.
For atomic orbitals basis,
- lapack: This method is only avaliable for serial version. For parallel version please use scalapack_gvx.
- genelpa: This method should be used if you choose localized orbitals.
- scalapack_gvx: Scalapack can also be used for localized orbitals.
- cusolver: This method needs building with CUDA and at least one gpu is available.
- cusolvermp: This method supports multi-GPU acceleration and needs building with CUDA。 Note that when using cusolvermp, you should set the number of MPI processes to be equal to the number of GPUs.
- elpa: The ELPA solver supports both CPU and GPU. By setting the device to GPU, you can launch the ELPA solver with GPU acceleration (provided that you have installed a GPU-supported version of ELPA, which requires you to manually compile and install ELPA, and the ABACUS should be compiled with -DUSE_ELPA=ON and -DUSE_CUDA=ON). The ELPA solver also supports multi-GPU acceleration.
If you set ks_solver=genelpa for basis_type=pw, the program will be stopped with an error message:
```
genelpa can not be used with plane wave basis.
```
Then the user has to correct the input file and restart the calculation.
Default:
- PW basis: cg.
- LCAO basis:
  - genelpa (if compiling option USE_ELPA has been set)
  - lapack (if compiling option ENABLE_MPI has not been set)
  - scalapack_gvx (if compiling option USE_ELPA has not been set and compiling option ENABLE_MPI has been set)
  - cusolver (if compiling option USE_CUDA has been set)

nbands#

Type: Integer
Description: The number of Kohn-Sham orbitals to calculate. It is recommended to setup this value, especially when smearing techniques are utilized, more bands should be included.
Default:
- nspin=1: max(1.2*occupied_bands, occupied_bands + 10)
- nspin=2: max(1.2*nelec_spin, nelec_spin + 10), in which nelec_spin = max(nelec_spin_up, nelec_spin_down)
- nspin=4: max(1.2*nelec, nelec + 20)

nelec#

Type: Real
Description:
- 0.0: the total number of electrons will be calculated by the sum of valence electrons (i.e. assuming neutral system).
- >0.0: this denotes the total number of electrons in the system. Must be less than 2*nbands.
Default: 0.0

nelec_delta#

Type: Real
Description: the total number of electrons will be calculated by nelec+nelec_delta.
Default: 0.0

nupdown#

Type: Real
Description:
- 0.0: no constrain apply to system.
- >0.0: this denotes the difference number of electrons between spin-up and spin-down in the system. The range of value must in [-nelec ~ nelec]. It is one method of constraint DFT, the fermi energy level will separate to E_Fermi_up and E_Fermi_down.
Default: 0.0

dft_functional#

Type: String
Description: In our package, the XC functional can either be set explicitly using the dft_functional keyword in INPUT file. If dft_functional is not specified, ABACUS will use the xc functional indicated in the pseudopotential file. On the other hand, if dft_functional is specified, it will overwrite the functional from pseudopotentials and performs calculation with whichever functional the user prefers. We further offer two ways of supplying exchange-correlation functional. The first is using ‘short-hand’ names such as ‘LDA’, ‘PBE’, ‘SCAN’. A complete list of ‘short-hand’ expressions can be found in the source code. The other way is only available when compiling with LIBXC, and it allows for supplying exchange-correlation functionals as combinations of LIBXC keywords for functional components, joined by a plus sign, for example, dft_functional=‘LDA_X_1D_EXPONENTIAL+LDA_C_1D_CSC’. The list of LIBXC keywords can be found on its website. In this way, we support all the LDA,GGA and mGGA functionals provided by LIBXC.

Furthermore, the old INPUT parameter exx_hybrid_type for hybrid functionals has been absorbed into dft_functional. Options are hf (pure Hartree-Fock), pbe0(PBE0), hse (Note: in order to use HSE functional, LIBXC is required). Note also that HSE has been tested while PBE0 has NOT been fully tested yet, and the maximum CPU cores for running exx in parallel is $N(N+1)/2$, with N being the number of atoms. And forces for hybrid functionals are not supported yet.

If set to opt_orb, the program will not perform hybrid functional calculation. Instead, it is going to generate opt-ABFs as discussed in this article.
Default: same as UPF file.

xc_temperature#

Type: Real
Description: specifies temperature when using temperature-dependent XC functionals (KSDT and so on).
Default : 0.0
Unit: Ry

pseudo_rcut#

Type: Real
Description: Cut-off of radial integration for pseudopotentials
Default: 15
Unit: Bohr

pseudo_mesh#

Type: Integer
Description:
- 0: use our own mesh for radial integration of pseudopotentials
- 1: use the mesh that is consistent with quantum espresso
Default: 0

nspin#

Type: Integer
Description: The number of spin components of wave functions.
- 1: Spin degeneracy
- 2: Collinear spin polarized.
- 4: For the case of noncollinear polarized, nspin will be automatically set to 4 without being specified by the user.
Default: 1

smearing_method#

Type: String
Description: It indicates which occupation and smearing method is used in the calculation.
- fixed: fixed occupations (available for non-coductors only)
- gauss or gaussian: Gaussian smearing method.
- mp: methfessel-paxton smearing method; recommended for metals.
- mp2: 2-nd methfessel-paxton smearing method; recommended for metals.
- mv or cold: marzari-vanderbilt smearing method.
- fd: Fermi-Dirac smearing method: $f=1/\{1+\exp[(E-\mu)/kT]\}$ and smearing_sigma below is the temperature $T$ (in Ry).
Default: gauss

smearing_sigma#

Type: Real
Description: Energy range for smearing.
Default: 0.015
Unit: Ry

smearing_sigma_temp#

Type: Real
Description: Energy range for smearing, smearing_sigma = 1/2 kB smearing_sigma_temp.
Default: 2 * smearing_sigma / kB.
Unit: K

mixing_type#

Type: String
Description: Charge mixing methods.
- plain: Just simple mixing.
- pulay: Standard Pulay method. P. Pulay Chemical Physics Letters, (1980)
- broyden: Simplified modified Broyden method. D.D. Johnson Physical Review B (1988)
In general, the convergence of the Broyden method is slightly faster than that of the Pulay method.
Default: broyden

mixing_beta#

Type: Real
Description: In general, the formula of charge mixing can be written as $\rho_{new} = \rho_{old} + \beta * \rho_{update}$, where $\rho_{new}$ represents the new charge density after charge mixing, $\rho_{old}$ represents the charge density in previous step, $\rho_{update}$ is obtained through various mixing methods, and $\beta$ is set by the parameter mixing_beta. A lower value of ‘mixing_beta’ results in less influence of $\rho_{update}$ on $\rho_{new}$, making the self-consistent field (SCF) calculation more stable. However, it may require more steps to achieve convergence. We recommend the following options:
- 0.8: nspin=1
- 0.4: nspin=2 and nspin=4
- 0: keep charge density unchanged, usually used for restarting with init_chg=file or testing.
- 0.1 or less: if convergence of SCF calculation is difficult to reach, please try 0 < mixing_beta < 0.1.
Note: For low-dimensional large systems, the setup of mixing_beta=0.1, mixing_ndim=20, and mixing_gg0=1.0 usually works well.
Default: 0.8 for nspin=1, 0.4 for nspin=2 and nspin=4.

mixing_beta_mag#

Type: Real
Description: Mixing parameter of magnetic density.
Default: 4*mixing_beta, but the maximum value is 1.6.

Note that mixing_beta_mag is not euqal to mixing_beta means that $\rho_{up}$ and $\rho_{down}$ mix independently from each other. This setting will fail for one case where the $\rho_{up}$ and $\rho_{down}$ of the ground state refers to different Kohn-Sham orbitals. For an atomic system, the $\rho_{up}$ and $\rho_{down}$ of the ground state refers to different Kohn-Sham orbitals. We all know Kohn-Sham orbitals are orthogonal to each other. So the mixture of $\rho_{up}$ and $\rho_{down}$ should be exactly independent, otherwise SCF cannot find the ground state forever. To sum up, please make sure mixing_beta_mag and mixing_gg0_mag exactly euqal to mixing_beta and mixing_gg0 if you calculate an atomic system.

mixing_ndim#

Type: Integer
Description: It indicates the mixing dimensions in Pulay or Broyden. Pulay and Broyden method use the density from previous mixing_ndim steps and do a charge mixing based on this density.

For systems that are difficult to converge, one could try increasing the value of ‘mixing_ndim’ to enhance the stability of the self-consistent field (SCF) calculation.
Default: 8

mixing_restart#

Type: double
Description: If the density difference between input and output drho is smaller than mixing_restart, SCF will restart at next step which means SCF will restart by using output charge density from perivos iteration as input charge density directly, and start a new mixing. Notice that mixing_restart will only take effect once in one SCF.
Default: 0

mixing_dmr#

Type: bool
Availability: Only for mixing_restart>=0.0
Description: At n-th iteration which is calculated by drho<mixing_restart, SCF will start a mixing for real-space density matrix by using the same coefficiences as the mixing of charge density.
Default: false

mixing_gg0#

Type: Real
Description: Whether to perfom Kerker scaling for charge density.
- >0: The high frequency wave vectors will be suppressed by multiplying a scaling factor $\frac{k^2}{k^2+gg0^2}$. Setting mixing_gg0 = 1.0 is normally a good starting point. Kerker preconditioner will be automatically turned off if mixing_beta <= 0.1.
- 0: No Kerker scaling is performed.
For systems that are difficult to converge, particularly metallic systems, enabling Kerker scaling may aid in achieving convergence.
Default: 1.0

mixing_gg0_mag#

Type: Real
Description: Whether to perfom Kerker preconditioner of magnetic density. Note: we do not recommand to open Kerker preconditioner of magnetic density unless the system is too hard to converge.
Default: 0.0

mixing_gg0_min#

Type: Real
Description: the minimum kerker coefficient
Default: 0.1

mixing_angle#

Type: Real
Availability: Only relevant for non-colinear calculations nspin=4.
Description: Normal broyden mixing can give the converged result for a given magnetic configuration. If one is not interested in the energies of a given magnetic configuration but wants to determine the ground state by relaxing the magnetic moments’ directions, one cannot rely on the standard Broyden mixing algorithm. To enhance the ability to find correct magnetic configuration for non-colinear calculations, ABACUS implements a promising mixing method proposed by J. Phys. Soc. Jpn. 82 (2013) 114706. Here, mixing_angle is the angle mixing parameter. In fact, only mixing_angle=1.0 is implemented currently.
- <=0: Normal broyden mixing for $m_{x}, m_{y}, m_{z}$
- >0: Angle mixing for the modulus $|m|$ with mixing_angle=1.0
Default: -10.0

Note: In new angle mixing, you should set mixing_beta_mag >> mixing_beta. The setup of mixing_beta=0.2, mixing_beta_mag=1.0 usually works well.

mixing_tau#

Type: Boolean
Availability: Only relevant for meta-GGA calculations.
Description: Whether to mix the kinetic energy density.
- True: The kinetic energy density will also be mixed. It seems for general cases, SCF converges fine even without this mixing. However, if there is difficulty in converging SCF for meta-GGA, it might be helpful to turn this on.
- False: The kinetic energy density will not be mixed.
Default: False

mixing_dftu#

Type: Boolean
Availability: Only relevant for DFT+U calculations.
Description: Whether to mix the occupation matrices.
- True: The occupation matrices will also be mixed by plain mixing. From experience this is not very helpful if the +U calculation does not converge.
- False: The occupation matrices will not be mixed.
Default: False

gamma_only#

Type: Integer
Availability: Only used in localized orbitals set
Description: Whether to use gamma_only algorithm.
- 0: more than one k-point is used and the ABACUS is slower compared to the gamma only algorithm.
- 1: ABACUS uses gamma only, the algorithm is faster and you don’t need to specify the k-points file.
Note: If gamma_only is set to 1, the KPT file will be overwritten. So make sure to turn off gamma_only for multi-k calculations.
Default: 0

printe#

Type: Integer
Description: Print out energy for each band for every printe step
Default: scf_nmax

scf_nmax#

Type: Integer
Description: This variable indicates the maximal iteration number for electronic iterations.
Default: 100

scf_thr#

Type: Real
Description: It’s the density threshold for electronic iteration. It represents the charge density error between two sequential densities from electronic iterations. Usually for local orbitals, usually 1e-6 may be accurate enough.
Default: 1.0e-9 (plane-wave basis), or 1.0e-7 (localized atomic orbital basis).

scf_ene_thr#

Type: Real
Description: It’s the energy threshold for electronic iteration. It represents the total energy error between two sequential densities from electronic iterations.
Default: -1.0. If the user does not set this parameter, it will not take effect.
Unit: eV

scf_thr_type#

Type: Integer
Description: Choose the calculation method of convergence criterion.
- 1: the criterion is defined as $\Delta\rho_G = \frac{1}{2}\iint{\frac{\Delta\rho(r)\Delta\rho(r')}{|r-r'|}d^3r d^3r'}$.
- 2: the criterion is defined as $\Delta\rho_R = \frac{1}{N_e}\int{|\Delta\rho(r)|d^3r}$, where $N_e$ is the number of electron.
Note: This parameter is still under testing and the default setting is usually sufficient.
Default: 1 (plane-wave basis), or 2 (localized atomic orbital basis).

scf_os_stop#

Type: bool
Description: For systems that are difficult to converge, the SCF process may exhibit oscillations in charge density, preventing further progress toward the specified convergence criteria and resulting in continuous oscillation until the maximum number of steps is reached; this greatly wastes computational resources. To address this issue, this function allows ABACUS to terminate the SCF process early upon detecting oscillations, thus reducing subsequent meaningless calculations. The detection of oscillations is based on the slope of the logarithm of historical drho values… To this end, Least Squares Method is used to calculate the slope of the logarithmically taken drho for the previous scf_os_ndim iterations. If the calculated slope is larger than scf_os_thr, stop the SCF.
- 0: The SCF will continue to run regardless of whether there is oscillation or not.
- 1: If the calculated slope is larger than scf_os_thr, stop the SCF.
Default: false

scf_os_thr#

Type: double
Description: The slope threshold to determine if the SCF is stuck in a charge density oscillation. If the calculated slope is larger than scf_os_thr, stop the SCF.
Default: -0.01

scf_os_ndim#

Type: int
Description: To determine the number of old iterations’ drho used in slope calculations.
Default: mixing_ndim

chg_extrap#

Type: String
Description: Methods to do extrapolation of density when ABACUS is doing geometry relaxations or molecular dynamics.
- atomic: atomic extrapolation.
- first-order: first-order extrapolation.
- second-order: second-order extrapolation.
Default: first-order (geometry relaxations), second-order (molecular dynamics), else atomic

lspinorb#

Type: Boolean
Description: Whether to consider spin-orbital coupling effect in the calculation.
- True: Consider spin-orbital coupling effect, and nspin is also automatically set to 4.
- False: Do not consider spin-orbital coupling effect.
Default: False

noncolin#

Type: Boolean
Description: Whether to allow non-collinear polarization, in which case the coupling between spin up and spin down will be taken into account.
- True: Allow non-collinear polarization, and nspin is also automatically set to 4.
- False: Do not allow non-collinear polarization.
Default: False

soc_lambda#

Type: Real
Availability: Relevant for soc calculations.
Description: Sometimes, for some real materials, both scalar-relativistic and full-relativistic can not describe the exact spin-orbit coupling. Artificial modulation may help in such cases.

soc_lambda, which has value range [0.0, 1.0] , is used for modulate SOC effect.

In particular, soc_lambda 0.0 refers to scalar-relativistic case and soc_lambda 1.0 refers to full-relativistic case.
Default: 1.0

Electronic structure (SDFT)#

These variables are used to control the parameters of stochastic DFT (SDFT), mix stochastic-deterministic DFT (MDFT), or complete-basis Chebyshev method (CT). In the following text, stochastic DFT is used to refer to these three methods. We suggest using SDFT to calculate high-temperature systems and we only support smearing_method “fd”. Both “scf” and “nscf” calculation are supported.

method_sto#

Type: Integer
Availability: esolver_type = sdft
Description: Different methods to do stochastic DFT
- 1: Calculate $T_n(\hat{h})\ket{\chi}$ twice, where $T_n(x)$ is the n-th order Chebyshev polynomial and $\hat{h}=\frac{\hat{H}-\bar{E}}{\Delta E}$ owning eigenvalues $\in(-1,1)$. This method cost less memory but is slower.
- 2: Calculate $T_n(\hat{h})\ket{\chi}$ once but needs much more memory. This method is much faster. Besides, it calculates $N_e$ with $\bra{\chi}\sqrt{\hat f}\sqrt{\hat f}\ket{\chi}$, which needs a smaller nche_sto. However, when the memory is not enough, only method 1 can be used.
- other: use 2
Default: 2

nbands_sto#

Type: Integer or string
Availability: esolver_type = sdft
Description: The number of stochastic orbitals
- > 0: Perform stochastic DFT. Increasing the number of bands improves accuracy and reduces stochastic errors, which scale as $1/\sqrt{N_{\chi}}$; To perform mixed stochastic-deterministic DFT, you should set nbands, which represents the number of KS orbitals.
- 0: Perform Kohn-Sham DFT.
- all: All complete basis sets are used to replace stochastic orbitals with the Chebyshev method (CT), resulting in the same results as KSDFT without stochastic errors.
Default: 256

nche_sto#

Type: Integer
Availability: esolver_type = sdft
Description: Chebyshev expansion orders for stochastic DFT.
Default: 100

emin_sto#

Type: Real
Availability: esolver_type = sdft
Description: Trial energy to guess the lower bound of eigen energies of the Hamiltonian Operator $\hat{H}$.
Default: 0.0
Unit: Ry

emax_sto#

Type: Real
Availability: esolver_type = sdft
Description: Trial energy to guess the upper bound of eigen energies of the Hamiltonian Operator $\hat{H}$.
Default: 0.0
Unit: Ry

seed_sto#

Type: Integer
Availability: esolver_type = sdft
Description: The random seed to generate stochastic orbitals.
- >= 0: Stochastic orbitals have the form of $\exp(i2\pi\theta(G))$, where $\theta$ is a uniform distribution in $(0,1)$.
- 0: the seed is decided by time(NULL).
- <= -1: Stochastic orbitals have the form of $\pm1$ with equal probability.
- -1: the seed is decided by time(NULL).
Default: 0

initsto_ecut#

Type: Real
Availability: esolver_type = sdft
Description: Stochastic wave functions are initialized in a large box generated by “4*initsto_ecut”. initsto_ecut should be larger than ecutwfc. In this method, SDFT results are the same when using different cores. Besides, coefficients of the same G are the same when ecutwfc is rising to initsto_ecut. If it is smaller than ecutwfc, it will be turned off.
Default: 0.0
Unit: Ry

initsto_freq#

Type: Integer
Availability: esolver_type = sdft
Description: Frequency (once each initsto_freq steps) to generate new stochastic orbitals when running md.
- positive integer: Update stochastic orbitals
- 0: Never change stochastic orbitals.
Default: 0

npart_sto#

Type: Integer
Availability: method_sto = 2 and out_dos = 1 or cal_cond = True
Description: Make memory cost to 1/npart_sto times of the previous one when running the post process of SDFT like DOS or conductivities.
Default: 1

Geometry relaxation#

These variables are used to control the geometry relaxation.

relax_method#

Type: String
Description: The methods to do geometry optimization.
- cg: using the conjugate gradient (CG) algorithm. Note that there are two implementations of the conjugate gradient (CG) method, see relax_new.
- bfgs: using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm.
- cg_bfgs: using the CG method for the initial steps, and switching to BFGS method when the force convergence is smaller than relax_cg_thr.
- sd: using the steepest descent (SD) algorithm.
- fire: the Fast Inertial Relaxation Engine method (FIRE), a kind of molecular-dynamics-based relaxation algorithm, is implemented in the molecular dynamics (MD) module. The algorithm can be used by setting calculation to md and md_type to fire. Also ionic velocities should be set in this case. See fire for more details.
Default: cg

relax_new#

Type: Boolean
Description: At around the end of 2022 we made a new implementation of the Conjugate Gradient (CG) method for relax and cell-relax calculations. But the old implementation was also kept.
- True: use the new implementation of CG method for relax and cell-relax calculations.
- False: use the old implementation of CG method for relax and cell-relax calculations.
Default: True

relax_scale_force#

Type: Real
Availability: only used when relax_new set to True
Description: The paramether controls the size of the first conjugate gradient step. A smaller value means the first step along a new CG direction is smaller. This might be helpful for large systems, where it is safer to take a smaller initial step to prevent the collapse of the whole configuration.
Default: 0.5

relax_nmax#

Type: Integer
Description: The maximal number of ionic iteration steps. If set to 0, the code performs a quick “dry run”, stopping just after initialization. This is useful to check for input correctness and to have the summary printed.
Default: 1 for SCF, 50 for relax and cell-relax calcualtions

relax_cg_thr#

Type: Real
Description: When move-method is set to cg_bfgs, a mixed algorithm of conjugate gradient (CG) method and Broyden–Fletcher–Goldfarb–Shanno (BFGS) method is used. The ions first move according to CG method, then switched to BFGS method when the maximum of force on atoms is reduced below the CG force threshold, which is set by this parameter.
Default: 0.5
Unit: eV/Angstrom

cal_force#

Type: Boolean
Description:
- True calculate the force at the end of the electronic iteration
- False no force calculation at the end of the electronic iteration
Default: False if calculation is set to scf, True if calculation is set to cell-relax, relax, or md.

force_thr#

Type: Real
Description: Threshold of the force convergence in Ry/Bohr. The threshold is compared with the largest force among all of the atoms. The recommended value for using atomic orbitals is 0.04 eV/Angstrom (0.0016 Ry/Bohr). The parameter is equivalent to force_thr_ev except for the unit. You may choose either you like.
Default: 0.001
Unit: Ry/Bohr (25.7112 eV/Angstrom)

force_thr_ev#

Type: Real
Description: Threshold of the force convergence in eV/Angstrom. The threshold is compared with the largest force among all of the atoms. The recommended value for using atomic orbitals is 0.04 eV/Angstrom (0.0016 Ry/Bohr). The parameter is equivalent to force_thr except for the unit. You may choose either you like.
Default: 0.0257112
Unit: eV/Angstrom (0.03889 Ry/Bohr)

force_thr_ev2#

Type: Real
Description: The calculated force will be set to 0 when it is smaller than the parameter force_thr_ev2.
Default: 0.0
Unit: eV/Angstrom

relax_bfgs_w1#

Type: Real
Description: This variable controls the Wolfe condition for Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm used in geometry relaxation. You can look into the paper Phys.Chem.Chem.Phys.,2000,2,2177 for more information.
Default: 0.01

relax_bfgs_w2#

Type: Real
Description: This variable controls the Wolfe condition for Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm used in geometry relaxation. You can look into the paper Phys.Chem.Chem.Phys.,2000,2,2177 for more information.
Default: 0.5

relax_bfgs_rmax#

Type: Real
Description: This variable is for geometry optimization. It stands for the maximal movement of all the atoms. The sum of the movements from all atoms can be increased during the optimization steps. However, it can not be larger than relax_bfgs_rmax
Unit: Bohr
Default: 0.8

relax_bfgs_rmin#

Type: Real
Description: This variable is for geometry optimization. It indicates the minimal movement of all the atoms. When the movement of all the atoms is smaller than relax_bfgs_rmin Bohr, and the force convergence is still not achieved, the calculation will break down.
Default: 1e-5
Unit: Bohr

relax_bfgs_init#

Type: Real
Description: This variable is for geometry optimization. It stands for the sum of initial movements of all of the atoms.
Default: 0.5
Unit: Bohr

cal_stress#

Type: Boolean
Description:
- True: calculate the stress at the end of the electronic iteration
- False: no calculation of the stress at the end of the electronic iteration
Default: True if calculation is cell-relax, False otherwise.

stress_thr#

Type: Real
Description: The threshold of the stress convergence. The threshold is compared with the largest component of the stress tensor.
Default: 0.5
Unit: kbar

press1, press2, press3#

Type: Real
Description: The external pressures along three axes. Positive input value is taken as compressive stress.
Default: 0
Unit: kbar

fixed_axes#

Type: String
Availability: only used when calculation set to cell-relax
Description: Axes that are fixed during cell relaxation. Possible choices are:
- None: default; all of the axes can relax
- volume: relaxation with fixed volume
- shape: fix shape but change volume (i.e. only lattice constant changes)
- a: fix a axis during relaxation
- b: fix b axis during relaxation
- c: fix c axis during relaxation
- ab: fix both a and b axes during relaxation
- ac: fix both a and c axes during relaxation
- bc: fix both b and c axes during relaxation

Note : fixed_axes = “shape” and “volume” are only available for relax_new = True

Default: None

fixed_ibrav#

Type: Boolean
Availability: Must be used along with relax_new set to True, and a specific latname must be provided
Description:
- True: the lattice type will be preserved during relaxation
- False: No restrictions are exerted during relaxation in terms of lattice type

Note: it is possible to use fixed_ibrav with fixed_axes, but please make sure you know what you are doing. For example, if we are doing relaxation of a simple cubic lattice (latname = “sc”), and we use fixed_ibrav along with fixed_axes = “volume”, then the cell is never allowed to move and as a result, the relaxation never converges.

Default: False

fixed_atoms#

Type: Boolean
Description:
- True: The direct coordinates of atoms will be preserved during variable-cell relaxation.
- False: No restrictions are exerted on positions of all atoms. However, users can still fix certain components of certain atoms by using the m keyword in STRU file. For the latter option, check the end of this instruction.
Default: False

cell_factor#

Type: Real
Description: Used in the construction of the pseudopotential tables. It should exceed the maximum linear contraction of the cell during a simulation.
Default: 1.2

Variables related to output information#

These variables are used to control the output of properties.

out_mul#

Type: Boolean
Availability: Numerical atomic orbital basis
Description: Whether to print the Mulliken population analysis result into OUT.${suffix}/mulliken.txt. In molecular dynamics calculations, the output frequency is controlled by out_interval.
Default: False

out_freq_elec#

Type: Integer
Description: The output frequency of the charge density (controlled by out_chg), wavefunction (controlled by out_wfc_pw or out_wfc_r), and density matrix of localized orbitals (controlled by out_dm).
- >0: Output them every out_freq_elec iteration numbers in electronic iterations.
- 0: Output them when the electronic iteration is converged or reaches the maximal iteration number.
Default: 0

out_chg#

Type: Integer [Integer](optional)
Description: The first integer controls whether to output the charge density on real space grids:
- 1: Output the charge density (in Bohr^-3) on real space grids into the density files in the folder OUT.${suffix}. The files are named as:
  - nspin = 1: SPIN1_CHG.cube;
  - nspin = 2: SPIN1_CHG.cube, and SPIN2_CHG.cube;
  - nspin = 4: SPIN1_CHG.cube, SPIN2_CHG.cube, SPIN3_CHG.cube, and SPIN4_CHG.cube.
- 2: On top of 1, also output the initial charge density. The files are named as:
  - nspin = 1: SPIN1_CHG_INI.cube
  - nspin = 2: SPIN1_CHG_INI.cube, and SPIN2_CHG_INI.cube;
  - nspin = 4: SPIN1_CHG_INI.cube, SPIN2_CHG_INI.cube, SPIN3_CHG_INI.cube, and SPIN4_CHG_INI.cube.
- -1: disable the charge density auto-back-up file {suffix}-CHARGE-DENSITY.restart, useful for large systems.
The second integer controls the precision of the charge density output, if not given, will use 3 as default. For purpose restarting from this file and other high-precision involved calculation, recommend to use 10.

The circle order of the charge density on real space grids is: x is the outer loop, then y and finally z (z is moving fastest).

If EXX(exact exchange) is calculated, (i.e. dft_fuctional==hse/hf/pbe0/scan0/opt_orb or rpa==True), the Hexx® files will be output in the folder OUT.${suffix} too, which can be read in NSCF calculation.

In molecular dynamics calculations, the output frequency is controlled by out_interval.
Default: 0 3

out_pot#

Type: Integer
Description:
- 1: Output the total local potential (i.e., local pseudopotential + Hartree potential + XC potential + external electric field (if exists) + dipole correction potential (if exists) + …) on real space grids (in Ry) into files in the folder OUT.${suffix}. The files are named as:
  - nspin = 1: SPIN1_POT.cube;
  - nspin = 2: SPIN1_POT.cube, and SPIN2_POT.cube;
  - nspin = 4: SPIN1_POT.cube, SPIN2_POT.cube, SPIN3_POT.cube, and SPIN4_POT.cube.
- 2: Output the electrostatic potential on real space grids into OUT.${suffix}/ElecStaticPot.cube. The Python script named tools/average_pot/aveElecStatPot.py can be used to calculate the average electrostatic potential along the z-axis and outputs it into ElecStaticPot_AVE.
  
  Please note that the total local potential refers to the local component of the self-consistent potential, excluding the non-local pseudopotential. The distinction between the local potential and the electrostatic potential is as follows: local potential = electrostatic potential + XC potential.
- 3: Apart from 1, also output the total local potential of the initial charge density. The files are named as:
  - nspin = 1: SPIN1_POT_INI.cube;
  - nspin = 2: SPIN1_POT_INI.cube, and SPIN2_POT_INI.cube;
  - nspin = 4: SPIN1_POT_INI.cube, SPIN2_POT_INI.cube, SPIN3_POT_INI.cube, and SPIN4_POT_INI.cube.
In molecular dynamics calculations, the output frequency is controlled by out_interval.
Default: 0

out_dm#

Type: Boolean
Availability: Numerical atomic orbital basis (gamma-only algorithm)
Description: Whether to output the density matrix of localized orbitals into files in the folder OUT.${suffix}. The files are named as:
- nspin = 1: SPIN1_DM;
- nspin = 2: SPIN1_DM, and SPIN2_DM.
Default: False

out_dm1#

Type: Boolean
Availability: Numerical atomic orbital basis (multi-k points)
Description: Whether to output the density matrix of localized orbitals into files in the folder OUT.${suffix}. The density matrices are written in the format of sparse matrices, as mentioned in out_mat_hs2. The files are named as:
- nspin = 1: data-DMR-sparse_SPIN0.csr;
- nspin = 2: data-DMR-sparse_SPIN0.csr, and data-DMR-sparse_SPIN1.csr.
Default: False

out_wfc_pw#

Type: Integer
Availability: Plane wave basis or get_wf calculation in numerical atomic orbital basis
Description:
- 1: Output the coefficients of wave functions into text files named OUT.${suffix}/WAVEFUNC${K}.txt, where ${K} is the index of k points.
- 2: results are stored in binary files named OUT.${suffix}/WAVEFUNC${K}.dat.
Default: 0

out_wfc_r#

Type: Boolean
Availability: Plane wave basis or get_wf calculation in numerical atomic orbital basis
Description: Whether to output real-space wave functions into OUT.suffix/wfc_realspace/wfc_realspace_${K}_${B}, where ${K} is the index of k points, ${B} is the index of bands.
Default: False

out_wfc_lcao#

Type: Integer
Availability: Numerical atomic orbital basis
Description: Whether to output the wavefunction coefficients into files in the folder OUT.${suffix}. The files are named as WFC_{GAMMA|K}{index of K point}, and if out_app_flag is false, the file name will also contains _ION{ION step}, where ION step is the index of ionic step:
- 0: no output
- 1: (txt format)
  - gamma-only: WFC_NAO_GAMMA1_ION1.txt or WFC_NAO_GAMMA1.txt, …;
  - non-gamma-only: WFC_NAO_K1_ION1.txt or WFC_NAO_K1.txt, …;
- 2: (binary format)
  - gamma-only: WFC_NAO_GAMMA1_ION1.dat or WFC_NAO_GAMMA1.dat, …;
  - non-gamma-only: WFC_NAO_K1_ION1.dat or WFC_NAO_K1.dat, …
The corresponding sequence of the orbitals can be seen in Basis Set.

Also controled by out_interval and out_app_flag.
Default: Flase

out_dos#

Type: Integer
Description: Whether to output the density of states (DOS). For more information, refer to the dos.md.
- 0: no output
- 1: output the density of states (DOS)
- 2:
  - lcao-only: output the density of states (DOS) and the projected density of states (PDOS)
Default: 0

out_band#

Type: Boolean [Integer](optional)
Description: Whether to output the band structure (in eV), optionally output precision can be set by a second parameter, default is 8. For more information, refer to the band.md
Default: False

out_proj_band#

Type: Boolean
Description: Whether to output the projected band structure. For more information, refer to the band.md
Default: False

out_stru#

Type: Boolean
Description: Whether to output structure files per ionic step in geometry relaxation calculations into OUT.${suffix}/STRU_ION${istep}_D, where ${istep} is the ionic step.
Default: False

out_bandgap#

Type: Boolean
Description: Whether to print the bandgap per electronic iteration into OUT.${suffix}/running_${calculation}.log. The value of bandgaps can be obtained by searching for the keyword:
- nupdown > 0: E_bandgap_up and E_bandgap_dw
- nupdown = 0: E_bandgap
Default: False

out_level#

Type: String
Description: Control the output level of information in OUT.${suffix}/running_${calculation}.log.
- ie: electronic iteration level, which prints useful information for electronic iterations;
- i: geometry relaxation level, which prints some information for geometry relaxations additionally;
- m: molecular dynamics level, which does not print some information for simplicity.
Default: ie

out_alllog#

Type: Boolean
Description: Whether to print information into individual logs from all ranks in an MPI run.
- True: Information from each rank will be written into individual files named OUT.${suffix}/running_${calculation}_${rank+1}.log.
- False: Information will only be written from rank 0 into a file named OUT.${suffix}/running_${calculation}.log.
Default: False

out_mat_hs#

Type: Boolean [Integer](optional)
Availability: Numerical atomic orbital basis
Description: Whether to print the upper triangular part of the Hamiltonian matrices (in Ry) and overlap matrices for each k point into files in the directory OUT.${suffix}. The second number controls precision. For more information, please refer to hs_matrix.md. Also controled by out_interval and out_app_flag.
Default: False 8

out_mat_tk#

Type: Boolean [Integer](optional)
Availability: Numerical atomic orbital basis
Description: Whether to print the upper triangular part of the kinetic matrices (in Ry) for each k point into OUT.${suffix}/data-i-T, where i is the index of k points (see OUT.${suffix}/kpoints). One may optionally provide a second parameter to specify the precision.
Default: False [8]

out_mat_r#

Type: Boolean
Availability: Numerical atomic orbital basis (not gamma-only algorithm)
Description: Whether to print the matrix representation of the position matrix (in Bohr) into a file named data-rR-tr in the directory OUT.${suffix}. If calculation is set to get_S, the position matrix can be obtained without scf iterations. For more information, please refer to position_matrix.md.
Default: False

out_mat_hs2#

Type: Boolean
Availability: Numerical atomic orbital basis (not gamma-only algorithm)
Description: Whether to print files containing the Hamiltonian matrix $H(R)$ (in Ry) and overlap matrix $S(R)$ into files in the directory OUT.${suffix}. For more information, please refer to hs_matrix.md.
Default: False

out_mat_t#

Type: Boolean
Availability: Numerical atomic orbital basis (not gamma-only algorithm)
Description: For LCAO calculations, if out_mat_t is set to 1, ABACUS will generate files containing the kinetic energy matrix $T(R)$ (in Ry). The format will be the same as the Hamiltonian matrix $H(R)$ and overlap matrix $S(R)$ as mentioned in out_mat_hs2. The name of the files will be data-TR-sparse_SPIN0.csr and so on. Also controled by out_interval and out_app_flag.
Default: False

out_mat_dh#

Type: Boolean
Availability: Numerical atomic orbital basis (not gamma-only algorithm)
Description: Whether to print files containing the derivatives of the Hamiltonian matrix (in Ry/Bohr). The format will be the same as the Hamiltonian matrix $H(R)$ and overlap matrix $S(R)$ as mentioned in out_mat_hs2. The name of the files will be data-dHRx-sparse_SPIN0.csr and so on. Also controled by out_interval and out_app_flag.
Default: False

out_mat_xc#

Type: Boolean
Availability: Numerical atomic orbital (NAO) and NAO-in-PW basis
Description: Whether to print the upper triangular part of the exchange-correlation matrices in Kohn-Sham orbital representation (unit: Ry): $\braket{\psi_i|V_\text{xc}^\text{(semi-)local}+V_\text{exx}+V_\text{DFTU}|\psi_j}$ for each k point into files in the directory OUT.${suffix}, which is useful for the subsequent GW calculation. (Note that currently DeePKS term is not included. ) The files are named k-$k-Vxc, the meaning of $kcorresponding to k point and spin is same as hs_matrix.md. The band (KS orbital) energy for each (k-point, spin, band) will be printed in the file OUT.${suffix}/vxc_out.dat. If EXX is calculated, the local and EXX part of band energy will also be printed in OUT.${suffix}/vxc_local_out.datand OUT.${suffix}/vxc_exx_out.dat, respectively. All the vxc*_out.dat files contains 3 integers (nk, nspin, nband) followed by nk*nspin*nband lines of energy Hartree and eV.
Default: False

out_eband_terms#

Type: Boolean
Availability: Numerical atomic orbital basis
Description: Whether to print the band energy terms separately in the file OUT.${suffix}/${term}_out.dat. The terms include the kinetic, pseudopotential (local + nonlocal), Hartree and exchange-correlation (including exact exchange if calculated).
Default: False

out_hr_npz/out_dm_npz#

Type: Boolean
Availability: Numerical atomic orbital basis
Description: Whether to print Hamiltonian matrices $H(R)$/density matrics $DM(R)$ in npz format. This feature does not work for gamma-only calculations. Currently only intended for internal usage.
Default: False

dm_to_rho#

Type: Boolean
Availability: Numerical atomic orbital basis
Description: Reads density matrix $DM(R)$ in npz format and creates electron density on grids. This feature does not work for gamma-only calculations. Only supports serial calculations. Currently only intended for internal usage.
Default: False

out_app_flag#

Type: Boolean
Availability: Numerical atomic orbital basis (not gamma-only algorithm)
Description: Whether to output $r(R)$, $H(R)$, $S(R)$, $T(R)$, $dH(R)$, $H(k)$, $S(k)$ and $wfc(k)$ matrices in an append manner during molecular dynamics calculations. Check input parameters out_mat_r, out_mat_hs2, out_mat_t, out_mat_dh, out_mat_hs and out_wfc_lcao for more information.
Default: true

out_ndigits#

Type: Integar
Availability: out_mat_hs 1 case presently.
Description: Controls the length of decimal part of output data, such as charge density, Hamiltonian matrix, Overlap matrix and so on.
Default: 8

out_interval#

Type: Integer
Description: Control the interval for printing charge density, local potential, electrostatic potential, Mulliken population analysis, $r(R)$, $H(R)$, $S(R)$, $T(R)$, $dH(R)$, $H(k)$, $S(k)$ and $\psi(k)$ matrices during molecular dynamics calculations. Check input parameters out_chg, out_pot, out_mul, out_mat_r, out_mat_hs2, out_mat_t, out_mat_dh, out_mat_hs and out_wfc_lcao for more information, respectively.
Default: 1

out_element_info#

Type: Boolean
Description: Whether to print element information into files in the directory OUT.${suffix}/${element_label}, including pseudopotential and orbital information of the element (in atomic Ryberg units).
Default: False

restart_save#

Type: Boolean
Availability: Numerical atomic orbital basis
Description: Whether to save charge density files per ionic step, which are used to restart calculations. According to the value of read_file_dir:
- auto: These files are saved in folder OUT.${suffix}/restart/;
- other: These files are saved in folder ${read_file_dir}/restart/.
If EXX(exact exchange) is calculated (i.e. dft_fuctional==hse/hf/pbe0/scan0/opt_orb or rpa==True), the Hexx® files for each processor will also be saved in the above folder, which can be read in EXX calculation with restart_load==True.
Default: False

rpa#

Type: Boolean
Description: Generate output files used in rpa calculations.
Default: False

nbands_istate#

Type: Integer
Availability: Only for LCAO, used when calculation = get_wf or calculation = get_pchg.
Description: The number of bands around the Fermi level you would like to calculate. get_wf means to calculate the envelope functions of wave functions $\Psi_{i}=\Sigma_{\mu}C_{i\mu}\Phi_{\mu}$, where $\Psi_{i}$ is the ith wave function with the band index $i$ and $\Phi_{\mu}$ is the localized atomic orbital set. get_pchg means to calculate the density of each wave function $|\Psi_{i}|^{2}$. Specifically, suppose we have highest occupied bands at 100th wave functions. And if you set this variable to 5, it will print five wave functions from 96th to 105th. But before all this can be carried out, the wave functions coefficients should be first calculated and written into a file by setting the flag out_wfc_lcao = 1.
Default: 5

bands_to_print#

Type: String
Availability: For both PW and LCAO. When basis_type = lcao, used when calculation = get_wf or calculation = get_pchg.
Description: Specifies the bands to calculate the wave functions/charge densities for, using a space-separated string of 0s and 1s, providing a more flexible selection compared to nbands_istate. Each digit in the string corresponds to a band, starting from the first band. A 1 indicates that the charge density should be calculated for that band, while a 0 means the band will be ignored. The parameter allows a compact and flexible notation (similar to ocp_set), for example the syntax 1 4*0 5*1 0 is used to denote the selection of bands: 1 means calculate for the first band, 4*0 skips the next four bands, 5*1 means calculate for the following five bands, and the final 0 skips the next band. It’s essential that the total count of bands does not exceed the total number of bands (nbands); otherwise, it results in an error, and the process exits. The input string must contain only numbers and the asterisk (*) for repetition, ensuring correct format and intention of band selection.
Default: none

if_separate_k#

Type: Boolean
Availability: Only for LCAO, used only when calculation = get_pchg and gamma_only is turned off.
Description: Specifies whether to write the partial charge densities for all k-points to individual files or merge them. Warning: Enabling symmetry may produce incorrect results due to incorrect k-point weights. Therefore, when calculating partial charge densities, it is strongly recommended to set symmetry = -1.
Default: false

out_elf#

Type: Integer [Integer](optional)
Availability: Only for Kohn-Sham DFT and Orbital Free DFT.
Description: Whether to output the electron localization function (ELF) in the folder OUT.${suffix}. The files are named as
- nspin = 1:
  - ELF.cube: ${\rm{ELF}} = \frac{1}{1+\chi^2}$, $\chi = \frac{\frac{1}{2}\sum_{i}{f_i |\nabla\psi_{i}|^2} - \frac{|\nabla\rho|^2}{8\rho}}{\frac{3}{10}(3\pi^2)^{2/3}\rho^{5/3}}$;
- nspin = 2:
  - ELF_SPIN1.cube, ELF_SPIN2.cube: ${\rm{ELF}}_\sigma = \frac{1}{1+\chi_\sigma^2}$, $\chi_\sigma = \frac{\frac{1}{2}\sum_{i}{f_i |\nabla\psi_{i,\sigma}|^2} - \frac{|\nabla\rho_\sigma|^2}{8\rho_\sigma}}{\frac{3}{10}(6\pi^2)^{2/3}\rho_\sigma^{5/3}}$;
  - ELF.cube: ${\rm{ELF}} = \frac{1}{1+\chi^2}$, $\chi = \frac{\frac{1}{2}\sum_{i,\sigma}{f_i |\nabla\psi_{i,\sigma}|^2} - \sum_{\sigma}{\frac{|\nabla\rho_\sigma|^2}{8\rho_\sigma}}}{\sum_{\sigma}{\frac{3}{10}(6\pi^2)^{2/3}\rho_\sigma^{5/3}}}$;
The second integer controls the precision of the kinetic energy density output, if not given, will use 3 as default. For purpose restarting from this file and other high-precision involved calculation, recommend to use 10.

In molecular dynamics calculations, the output frequency is controlled by out_interval.
Default: 0 3

Density of states#

These variables are used to control the calculation of DOS. Detailed introduction

dos_edelta_ev#

Type: Real
Description: the step size in writing Density of States (DOS)
Default: 0.01
Unit: eV

dos_sigma#

Type: Real
Description: the width of the Gaussian factor when obtaining smeared Density of States (DOS)
Default: 0.07
Unit: eV

dos_scale#

Type: Real
Description: Defines the energy range of DOS output as (emax-emin)*(1+dos_scale), centered at (emax+emin)/2. This parameter will be used when dos_emin and dos_emax are not set.
Default: 0.01
Unit: eV

dos_emin_ev#

Type: Real
Description: the minimal range for Density of States (DOS)
- If set, “dos_scale” will be ignored.
Default: Minimal eigenenergy of $\hat{H}$
Unit: eV

dos_emax_ev#

Type: Real
Description: the maximal range for Density of States (DOS)
- If set, “dos_scale” will be ignored.
Default: Maximal eigenenergy of $\hat{H}$
Unit: eV

dos_nche#

Type: Integer The order of Chebyshev expansions when using Stochastic Density Functional Theory (SDFT) to calculate DOS.
Default: 100

NAOs#

These variables are used to control the generation of numerical atomic orbitals (NAOs), whose radial parts are linear combinations of spherical Bessel functions with a node (i.e., evaluate to zero) at the cutoff radius. In plane-wave-based calculations, necessary information will be printed into OUT.${suffix}/orb_matrix.${i}.dat, which serves as an input file for the generation of NAOs. Please check SIAB package for more information.

bessel_nao_ecut#

Type: Real
Description: “Energy cutoff” (in Ry) of spherical Bessel functions. The number of spherical Bessel functions that constitute the radial parts of NAOs is determined by sqrt(bessel_nao_ecut)$\times$bessel_nao_rcut/$\pi$.
Default: ecutwfc

bessel_nao_tolerence#

Type: Real
Description: tolerance when searching for the zeros of spherical Bessel functions.
Default: 1.0e-12

bessel_nao_rcut#

Type: Real
Description: Cutoff radius (in Bohr) and the common node of spherical Bessel functions used to construct the NAOs.
Default: 6.0

bessel_nao_smooth#

Type: Boolean
Description: if True, NAOs will be smoothed near the cutoff radius by $1-\exp\left(-\frac{(r-r_{cut})^2}{2\sigma^2}\right)$. See bessel_nao_rcut for $r_{cut}$ and bessel_nao_sigma for $\sigma$.
Default: True

bessel_nao_sigma#

Type: Real
Description: Smoothing range (in Bohr). See also bessel_nao_smooth.
Default: 0.1

DeePKS#

These variables are used to control the usage of DeePKS method (a comprehensive data-driven approach to improve the accuracy of DFT). Warning: this function is not robust enough for the current version. Please try the following variables at your own risk:

deepks_out_labels#

Type: Boolean
Availability: numerical atomic orbital basis
Description: Print labels and descriptors for DeePKS training in OUT.${suffix}. The names of these files start with “deepks”.
Note: In LCAO calculation, the path of a numerical descriptor (an orb file) is needed to be specified under the NUMERICAL_DESCRIPTOR tag in the STRU file. For example:
```
NUMERICAL_ORBITAL
H_gga_8au_60Ry_2s1p.orb
O_gga_7au_60Ry_2s2p1d.orb

NUMERICAL_DESCRIPTOR
jle.orb
```
Default: False

deepks_scf#

Type: Boolean
Availability: numerical atomic orbital basis
Description: perform self-consistent field iteration in DeePKS method
Note: A trained, traced model file is needed.
Default: False

deepks_equiv#

Type: Boolean
Availability: numerical atomic orbital basis
Description: whether to use equivariant version of DeePKS
Note: the equivariant version of DeePKS-kit is still under development, so this feature is currently only intended for internal usage.
Default: False

deepks_model#

Type: String
Availability: numerical atomic orbital basis and deepks_scf is true
Description: the path of the trained, traced neural network model file generated by deepks-kit
Default: None

bessel_descriptor_lmax#

Type: Integer
Availability: gen_bessel calculation
Description: the maximum angular momentum of the Bessel functions generated as the projectors in DeePKS
NOte: To generate such projectors, set calculation type to gen_bessel in ABACUS. See also calculation.
Default: 2

bessel_descriptor_ecut#

Type: Real
Availability: gen_bessel calculation
Description: energy cutoff of Bessel functions
Default: same as ecutwfc
Unit: Ry

bessel_descriptor_tolerence#

Type: Real
Availability: gen_bessel calculation
Description: tolerance for searching the zeros of Bessel functions
Default: 1.0e-12

bessel_descriptor_rcut#

Type: Real
Availability: gen_bessel calculation
Description: cutoff radius of Bessel functions
Default: 6.0
Unit: Bohr

bessel_descriptor_smooth#

Type: Boolean
Availability: gen_bessel calculation
Description: smooth the Bessel functions at radius cutoff
Default: False

bessel_descriptor_sigma#

Type: Real
Availability: gen_bessel calculation
Description: smooth parameter at the cutoff radius of projectors
Default: 0.1
Unit: Bohr

deepks_bandgap#

Type: Boolean
Availability: numerical atomic orbital basis and deepks_scf is true
Description: include bandgap label for DeePKS training
Default: False

deepks_v_delta#

Type: int
Availability: numerical atomic orbital basis
Description: Include V_delta label for DeePKS training. When deepks_out_labels is true and deepks_v_delta > 0, ABACUS will output h_base.npy, v_delta.npy and h_tot.npy(h_tot=h_base+v_delta). Meanwhile, when deepks_v_delta equals 1, ABACUS will also output v_delta_precalc.npy, which is used to calculate V_delta during DeePKS training. However, when the number of atoms grows, the size of v_delta_precalc.npy will be very large. In this case, it’s recommended to set deepks_v_delta as 2, and ABACUS will output psialpha.npy and grad_evdm.npy but not v_delta_precalc.npy. These two files are small and can be used to calculate v_delta_precalc in the procedure of training DeePKS.
Default: 0

deepks_out_unittest#

Type: Boolean
Description: generate files for constructing DeePKS unit test
Note: Not relevant when running actual calculations. When set to 1, ABACUS needs to be run with only 1 process.
Default: False

OFDFT: orbital free density functional theory#

of_kinetic#

Type: String
Availability: OFDFT
Description: The type of KEDF (kinetic energy density functional).
- wt: Wang-Teter.
- tf: Thomas-Fermi.
- vw: von Weizsäcker.
- tf+: TF$\rm{\lambda}$vW, the parameter $\rm{\lambda}$ can be set by of_vw_weight.
- lkt: Luo-Karasiev-Trickey.
Default: wt

of_method#

Type: String
Availability: OFDFT
Description: The optimization method used in OFDFT.
- cg1: Polak-Ribiere. Standard CG algorithm.
- cg2: Hager-Zhang (generally faster than cg1).
- tn: Truncated Newton algorithm.
Default:tn

of_conv#

Type: String
Availability: OFDFT
Description: Criterion used to check the convergence of OFDFT.
- energy: Ttotal energy changes less than of_tole.
- potential: The norm of potential is less than of_tolp.
- both: Both energy and potential must satisfy the convergence criterion.
Default: energy

of_tole#

Type: Real
Availability: OFDFT
Description: Tolerance of the energy change for determining the convergence.
Default: 2e-6
Unit: Ry

of_tolp#

Type: Real
Availability: OFDFT
Description: Tolerance of potential for determining the convergence.
Default: 1e-5
Unit: Ry

of_tf_weight#

Type: Real
Availability: OFDFT with of_kinetic=tf, tf+, wt
Description: Weight of TF KEDF (kinetic energy density functional).
Default: 1.0

of_vw_weight#

Type: Real
Availability: OFDFT with of_kinetic=vw, tf+, wt, lkt
Description: Weight of vW KEDF (kinetic energy density functional).
Default: 1.0

of_wt_alpha#

Type: Real
Availability: OFDFT with of_kinetic=wt
Description: Parameter alpha of WT KEDF (kinetic energy density functional).
Default: $5/6$

of_wt_beta#

Type: Real
Availability: OFDFT with of_kinetic=wt
Description: Parameter beta of WT KEDF (kinetic energy density functional).
Default: $5/6$

of_wt_rho0#

Type: Real
Availability: OFDFT with of_kinetic=wt
Description: The average density of system.
Default: 0.0
Unit: Bohr^-3

of_hold_rho0#

Type: Boolean
Availability: OFDFT with of_kinetic=wt
Description: Whether to fix the average density rho0.
- True: rho0 will be fixed even if the volume of system has changed, it will be set to True automatically if of_wt_rho0 is not zero.
- False: rho0 will change if volume of system has changed.
Default: False

of_lkt_a#

Type: Real
Availability: OFDFT with of_kinetic=lkt
Description: Parameter a of LKT KEDF (kinetic energy density functional).
Default: 1.3

of_read_kernel#

Type: Boolean
Availability: OFDFT with of_kinetic=wt
Description: Whether to read in the kernel file.
- True: The kernel of WT KEDF (kinetic energy density functional) will be filled from the file specified by of_kernel_file.
- False: The kernel of WT KEDF (kinetic energy density functional) will be filled from formula.
Default: False

of_kernel_file#

Type: String
Availability: OFDFT with of_read_kernel=True
Description: The name of WT kernel file.
Default: WTkernel.txt

of_full_pw#

Type: Boolean
Availability: OFDFT
Description: Whether to use full planewaves.
- True: Ecut will be ignored while collecting planewaves, so that all planewaves will be used in FFT.
- False: Only use the planewaves inside ecut, the same as KSDFT.
Default: True

of_full_pw_dim#

Type: Integer
Availability: OFDFT with of_full_pw = True
Description: Specify the parity of FFT dimensions.
- 0: either odd or even.
- 1: odd only.
- 2: even only.
Note: Even dimensions may cause slight errors in FFT. It should be ignorable in ofdft calculation, but it may make Cardinal B-spline interpolation unstable, so please set of_full_pw_dim = 1 if nbspline != -1.
Default: 0

Electric field and dipole correction#

These variables are relevant to electric field and dipole correction

efield_flag#

Type: Boolean
Description: added the electric field.
- True: A saw-like potential simulating an electric field is added to the bare ionic potential.
- False: Not added the electric field.
Default: False

dip_cor_flag#

Type: Boolean
Availability: with dip_cor_flag = True and efield_flag = True.
Description: Added a dipole correction to the bare ionic potential.
- True：A dipole correction is also added to the bare ionic potential.
- False: A dipole correction is not added to the bare ionic potential.

Note: If you want no electric field, parameter efield_amp should be zero. Must be used ONLY in a slab geometry for surface alculations, with the discontinuity FALLING IN THE EMPTY SPACE.

Default: False

efield_dir#

Type: Integer
Availability: with efield_flag = True.
Description: The direction of the electric field or dipole correction is parallel to the reciprocal lattice vector, so the potential is constant in planes defined by FFT grid points, efield_dir can set to 0, 1 or 2.
- 0: parallel to $b_1=\frac{2\pi(a_2\times a_3)}{a_1\cdot(a_2\times a_3)}$
- 1: parallel to $b_2=\frac{2\pi(a_3\times a_1)}{a_1\cdot(a_2\times a_3)}$
- 2: parallel to $b_3=\frac{2\pi(a_1\times a_2)}{a_1\cdot(a_2\times a_3)}$
Default: 2

efield_pos_max#

Type: Real
Availability: with efield_flag = True.
Description: Position of the maximum of the saw-like potential along crystal axis efield_dir, within the unit cell, 0 <= efield_pos_max < 1.
Default: Autoset to center of vacuum - width of vacuum / 20

efield_pos_dec#

Type: Real
Availability: with efield_flag = True.
Description: Zone in the unit cell where the saw-like potential decreases, 0 < efield_pos_dec < 1.
Default: Autoset to width of vacuum / 10

efield_amp#

Type: Real
Availability: with efield_flag = True.
Description: Amplitude of the electric field. The saw-like potential increases with slope efield_amp in the region from efield_pos_max+efield_pos_dec-1) to (efield_pos_max), then decreases until (efield_pos_max+efield_pos_dec), in units of the crystal vector efield_dir.

Note: The change of slope of this potential must be located in the empty region, or else unphysical forces will result.

Default: 0.0
Unit: a.u., 1 a.u. = 51.4220632*10^10 V/m.

Gate field (compensating charge)#

These variables are relevant to gate field (compensating charge) Detailed introduction

gate_flag#

Type: Boolean
Description: Controls the addition of compensating charge by a charged plate for charged cells.
- true: A charged plate is placed at the zgate position to add compensating charge. The direction is determined by efield_dir.
- false: No compensating charge is added.
Default: false

zgate#

Type: Real
Description: position of the charged plate in the unit cell
Unit: Unit cell size
Default: 0.5
Constraints: 0 <= zgate < 1

block#

Type: Boolean
Description: Controls the addition of a potential barrier to prevent electron spillover.
- true: A potential barrier is added from block_down to block_up with a height of block_height. If dip_cor_flag is set to true, efield_pos_dec is used to smoothly increase and decrease the potential barrier.
- false: No potential barrier is added.
Default: false

block_down#

Type: Real
Description: lower beginning of the potential barrier
Unit: Unit cell size
Default: 0.45
Constraints: 0 <= block_down < block_up < 1

block_up#

Type: Real
Description: upper beginning of the potential barrier
Unit: Unit cell size
Default: 0.55
Constraints: 0 <= block_down < block_up < 1

block_height#

Type: Real
Description: height of the potential barrier
Unit: Rydberg
Default: 0.1

Exact Exchange#

These variables are relevant when using hybrid functionals.

Availablity: dft_functional==hse/hf/pbe0/scan0/opt_orb or rpa==True, and basis_type==lcao/lcao_in_pw

exx_hybrid_alpha#

Type: Real
Description: fraction of Fock exchange in hybrid functionals, so that $E_{X}=\alpha E_{X}+(1-\alpha)E_{X,\text{LDA/GGA}}$
Default:
- 1: if dft_functional==hf
- 0.25: else

exx_hse_omega#

Type: Real
Description: range-separation parameter in HSE functional, such that $1/r=\text{erfc}(\omega r)/r+\text{erf}(\omega r)/r$
Default: 0.11

exx_separate_loop#

Type: Boolean
Description: There are two types of iterative approaches provided by ABACUS to evaluate Fock exchange.
- False: Start with a GGA-Loop, and then Hybrid-Loop, in which EXX Hamiltonian $H_{exx}$ is updated with electronic iterations.
- True: A two-step method is employed, i.e. in the inner iterations, density matrix is updated, while in the outer iterations, $H_{exx}$ is calculated based on density matrix that converges in the inner iteration.
Default: True

exx_hybrid_step#

Type: Integer
Availability: exx_separate_loop==1
Description: the maximal iteration number of the outer-loop, where the Fock exchange is calculated
Default: 100

exx_mixing_beta#

Type: Real
Availability: exx_separate_loop==1
Description: mixing_beta for densty matrix in each iteration of the outer-loop
Default: 1.0

exx_lambda#

Type: Real
Availability: basis_type==lcao_in_pw
Description: It is used to compensate for divergence points at G=0 in the evaluation of Fock exchange using lcao_in_pw method.
Default: 0.3

exx_pca_threshold#

Type: Real
Description: To accelerate the evaluation of four-center integrals ($ik|jl$), the product of atomic orbitals are expanded in the basis of auxiliary basis functions (ABF): $\Phi_{i}\Phi_{j}\sim C^{k}_{ij}P_{k}$. The size of the ABF (i.e. number of $P_{k}$) is reduced using principal component analysis. When a large PCA threshold is used, the number of ABF will be reduced, hence the calculation becomes faster. However, this comes at the cost of computational accuracy. A relatively safe choice of the value is 1e-4.
Default: 1E-4

exx_c_threshold#

Type: Real
Description: See also the entry exx_pca_threshold. Smaller components (less than exx_c_threshold) of the $C^{k}_{ij}$ matrix are neglected to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-4.
Default: 1E-4

exx_v_threshold#

Type: Real
Description: See also the entry exx_pca_threshold. With the approximation $\Phi_{i}\Phi_{j}\sim C^{k}_{ij}P_{k}$, the four-center integral in Fock exchange is expressed as $(ik|jl)=\Sigma_{a,b}C^{a}_{ij}V_{ab}C^{b}_{kl}$, where $V_{ab}=(P_{a}|P_{b})$ is a double-center integral. Smaller values of the V matrix can be truncated to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 0, i.e. no truncation.
Default: 1E-1

exx_dm_threshold#

Type: Real
Description: The Fock exchange can be expressed as $\Sigma_{k,l}(ik|jl)D_{kl}$ where D is the density matrix. Smaller values of the density matrix can be truncated to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-4.
Default: 1E-4

exx_c_grad_threshold#

Type: Real
Description: See also the entry exx_pca_threshold. $\nabla C^{k}_{ij}$ is used in force and stress. Smaller components (less than exx_c_grad_threshold) of the $\nabla C^{k}_{ij}$ matrix are neglected to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-4.
Default: 1E-4

exx_v_grad_threshold#

Type: Real
Description: See also the entry exx_pca_threshold. With the approximation $\Phi_{i}\Phi_{j}\sim C^{k}_{ij}P_{k}$, the four-center integral in Fock exchange is expressed as $(ik|jl)=\Sigma_{a,b}C^{a}_{ij}V_{ab}C^{b}_{kl}$, where $V_{ab}=(P_{a}|P_{b})$ is a double-center integral. $\nabla V_{ab}$ is used in force and stress. Smaller values of the V matrix can be truncated to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 0, i.e. no truncation.
Default: 1E-1

exx_schwarz_threshold#

Type: Real
Description: In practice the four-center integrals are sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each integral before carrying out explicit evaluations. Those that are smaller than exx_schwarz_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-5. (Currently not used)
Default: 0

exx_cauchy_threshold#

Type: Real
Description: In practice the Fock exchange matrix is sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each matrix element before carrying out explicit evaluations. Those that are smaller than exx_cauchy_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-7.
Default: 1E-7

exx_cauchy_force_threshold#

Type: Real
Description: In practice the Fock exchange matrix in force is sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each matrix element before carrying out explicit evaluations. Those that are smaller than exx_cauchy_force_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-7.
Default: 1E-7

exx_cauchy_stress_threshold#

Type: Real
Description: In practice the Fock exchange matrix in stress is sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each matrix element before carrying out explicit evaluations. Those that are smaller than exx_cauchy_stress_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-7.
Default: 1E-7

exx_ccp_threshold#

Type: Real
Description: It is related to the cutoff of on-site Coulomb potentials. (Currently not used)
Default: 1e-8

exx_ccp_rmesh_times#

Type: Real
Description: This parameter determines how many times larger the radial mesh required for calculating Columb potential is to that of atomic orbitals. For HSE, setting it to 1 is enough. But for PBE0, a much larger number must be used.
Default:
- 1.5: if dft_functional==hse
- 5: else

exx_distribute_type#

Type: String
Description: When running in parallel, the evaluation of Fock exchange is done by distributing atom pairs on different processes, then gather the results. exx_distribute_type governs the mechanism of distribution. Available options are htime, order, kmean1 and kmeans2.
- order: Atom pairs are simply distributed by their orders.
- htime: The balance in time is achieved on each processor, hence if the memory is sufficient, this is the recommended method.
- kmeans1 , kmeans2: Two methods where the k-means clustering method is used to reduce memory requirement. They might be necessary for very large systems. (Currently not used)
Default: htime

exx_opt_orb_lmax#

Type: Integer
Availability: dft_functional==opt_orb
Description: The maximum l of the spherical Bessel functions, when the radial part of opt-ABFs are generated as linear combinations of spherical Bessel functions. A reasonable choice is 2.
Default: 0

exx_opt_orb_ecut#

Type: Real
Availability: dft_functional==opt_orb
Description: The cut-off of plane wave expansion, when the plane wave basis is used to optimize the radial ABFs. A reasonable choice is 60.
Default: 0
Unit: Ry

exx_opt_orb_tolerence#

Type: Real
Availability: dft_functional==opt_orb
Description: The threshold when solving for the zeros of spherical Bessel functions. A reasonable choice is 1e-12.
Default: 0

exx_real_number#

Type: Boolean
Description:
- True: Enforce LibRI to use double data type.
- False: Enforce LibRI to use complex data type.
Default: depends on the gamma_only option
- True: if gamma_only
- False: else

rpa_ccp_rmesh_times#

Type: Real
Description: How many times larger the radial mesh required is to that of atomic orbitals in the postprocess calculation of the bare Coulomb matrix for RPA, GW, etc.
Default: 10

exx_symmetry_realspace#

Type: Boolean
Availability: symmetry==1 and exx calculation (dft_fuctional==hse/hf/pbe0/scan0/opt_orb or rpa==True)
Description:
- False: only rotate k-space density matrix D(k) from irreducible k-points to accelerate diagonalization
- True: rotate both D(k) and Hexx® to accelerate both diagonalization and EXX calculation
Default: True

out_ri_cv#

Type: Boolean
Description: Whether to output the coefficient tensor C® and ABFs-representation Coulomb matrix V® for each atom pair and cell in real space.
Default: false

Molecular dynamics#

These variables are used to control molecular dynamics calculations. For more information, please refer to md.md in detail.

md_type#

Type: String
Description: Control the algorithm to integrate the equation of motion for molecular dynamics (MD), see md.md in detail.
- fire: a MD-based relaxation algorithm, named fast inertial relaxation engine.
- nve: NVE ensemble with velocity Verlet algorithm.
- nvt: NVT ensemble, see md_thermostat in detail.
- npt: Nose-Hoover style NPT ensemble, see md_pmode in detail.
- langevin: NVT ensemble with Langevin thermostat, see md_damp in detail.
- msst: MSST method, see msst_direction, msst_vel, msst_qmass, msst_vis, msst_tscale in detail.
Default: nvt

md_nstep#

Type: Integer
Description: The total number of molecular dynamics steps.
Default: 10

md_dt#

Type: Real
Description: The time step used in molecular dynamics calculations.
Default: 1.0
Unit: fs

md_thermostat#

Type: String
Description: Specify the temperature control method used in NVT ensemble.
- nhc: Nose-Hoover chain, see md_tfreq and md_tchain in detail.
- anderson: Anderson thermostat, see md_nraise in detail.
- berendsen: Berendsen thermostat, see md_nraise in detail.
- rescaling: velocity Rescaling method 1, see md_tolerance in detail.
- rescale_v: velocity Rescaling method 2, see md_nraise in detail.
Default: nhc

md_tfirst, md_tlast#

Type: Real
Description: The temperature used in molecular dynamics calculations.

If md_tfirst is unset or less than zero, init_vel is autoset to be true. If init_vel is true, the initial temperature will be determined by the velocities read from STRU. In this case, if velocities are unspecified in STRU, the initial temperature is set to zero.

If md_tfirst is set to a positive value and init_vel is true simultaneously, please make sure they are consistent, otherwise abacus will exit immediately.

Note that md_tlast is only used in NVT/NPT simulations. If md_tlast is unset or less than zero, md_tlast is set to md_tfirst. If md_tlast is set to be different from md_tfirst, ABACUS will automatically change the temperature from md_tfirst to md_tlast.
Default: No default
Unit: K

md_restart#

Type: Boolean
Description: Control whether to restart molecular dynamics calculations and time-dependent density functional theory calculations.
- True: ABACUS will read in ${read_file_dir}/Restart_md.dat to determine the current step ${md_step}, then read in the corresponding STRU_MD_${md_step} in the folder OUT.$suffix/STRU/ automatically. For tddft, ABACUS will also read in WFC_NAO_K${kpoint} of the last step (You need to set out_wfc_lcao=1 and out_app_flag=0 to obtain this file).
- False: ABACUS will start molecular dynamics calculations normally from the first step.
Default: False

md_restartfreq#

Type: Integer
Description: The output frequency of OUT.${suffix}/Restart_md.dat and structural files in the directory OUT.${suffix}/STRIU/, which are used to restart molecular dynamics calculations, see md_restart in detail.
Default: 5

md_dumpfreq#

Type: Integer
Description: The output frequency of OUT.${suffix}/MD_dump in molecular dynamics calculations, which including the information of lattices and atoms.
Default: 1

dump_force#

Type: Boolean
Description: Whether to output atomic forces into the file OUT.${suffix}/MD_dump.
Default: True

dump_vel#

Type: Boolean
Description: Whether to output atomic velocities into the file OUT.${suffix}/MD_dump.
Default: True

dump_virial#

Type: Boolean
Description: Whether to output lattice virials into the file OUT.${suffix}/MD_dump.
Default: True

md_seed#

Type: Integer
Description: The random seed to initialize random numbers used in molecular dynamics calculations.
- < 0: No srand() function is called.
- >= 0: The function srand(md_seed) is called.
Default: -1

md_tfreq#

Type: Real
Description: Control the frequency of temperature oscillations during the simulation. If it is too large, the temperature will fluctuate violently; if it is too small, the temperature will take a very long time to equilibrate with the atomic system.

Note: It is a system-dependent empirical parameter, ranging from 1/(40*md_dt) to 1/(100*md_dt). An improper choice might lead to the failure of jobs.
Default: 1/40/md_dt
Unit: $\mathrm{fs^{-1}}$

md_tchain#

Type: Integer
Description: Number of thermostats coupled with the particles in the NVT/NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.
Default: 1

md_pmode#

Type: String
Description: Specify the cell fluctuation mode in NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.
- iso: The three diagonal elements of the lattice are fluctuated isotropically.
- aniso: The three diagonal elements of the lattice are fluctuated anisotropically.
- tri: The lattice must be a lower-triangular matrix, and all six freedoms are fluctuated.
Default: iso
Relavent: md_tfreq, md_tchain, md_pcouple, md_pfreq, and md_pchain.

ref_cell_factor#

Type: Real
Description: Construct a reference cell bigger than the initial cell. The reference cell has to be large enough so that the lattice vectors of the fluctuating cell do not exceed the reference lattice vectors during MD. Typically, 1.02 ~ 1.10 is sufficient. However, the cell fluctuations depend on the specific system and thermodynamic conditions. So users must test for a proper choice. This parameters should be used in conjunction with erf_ecut, erf_height, and erf_sigma.
Default: 1.0

md_pcouple#

Type: String
Description: The coupled lattice vectors will scale proportionally in NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.
- none: Three lattice vectors scale independently.
- xyz: Lattice vectors x, y, and z scale proportionally.
- xy: Lattice vectors x and y scale proportionally.
- xz: Lattice vectors x and z scale proportionally.
- yz: Lattice vectors y and z scale proportionally.
Default: none

md_pfirst, md_plast#

Type: Real
Description: The target pressure used in NPT ensemble simulations, the default value of md_plast is md_pfirst. If md_plast is set to be different from md_pfirst, ABACUS will automatically change the target pressure from md_pfirst to md_plast.
Default: -1.0
Unit: kbar

md_pfreq#

Type: Real
Description: The frequency of pressure oscillations during the NPT ensemble simulation. If it is too large, the pressure will fluctuate violently; if it is too small, the pressure will take a very long time to equilibrate with the atomic system.

Note: It is a system-dependent empirical parameter. An improper choice might lead to the failure of jobs.
Default: 1/400/md_dt
Unit: $\mathrm{kbar^{-1}}$

md_pchain#

Type: Integer
Description: The number of thermostats coupled with the barostat in the NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.
Default: 1

lj_rule#

Type: Integer
Description: The Lennard-Jones potential between two atoms equals: $$V_{LJ}(r_{ij})=4\epsilon_{ij}\left(\left(\frac{\sigma_{ij}}{r_{ij}}\right)^{12}-\left(\frac{\sigma_{ij}}{r_{ij}}\right)^{6}\right)=\frac{C_{ij}^{(12)}}{{r_{ij}}^{12}}-\frac{C_{ij}^{(6)}}{{r_{ij}}^{6}}.$$

The parameters lj_epsilon and lj_sigma should be multiple-component vectors. For example, there are two choices in the calculations of 3 atom species:

Supply six-component vectors that describe the interactions between all possible atom pairs. The six-component vectors represent lower triangular symmetric matrixs, and the correspondence between the vector component $\sigma _k$ and the matrix element $\sigma (i,j)$ is $$k= i(i+1)/2 +j$$

Supply three-component vectors that describe the interactions between atoms of the same species. In this case, two types of combination rules can be used to construct non-diagonal elements in the parameter matrix.
- 1: geometric average: $$\begin{array}{rcl}C_{ij}^{(6)}&=&\left(C_{ii}^{(6)}C_{jj}^{(6)}\right)^{1/2}\\C_{ij}^{(12)}&=&\left(C_{ii}^{(12)}C_{jj}^{(12)}\right)^{1/2}\end{array}$$
- 2: arithmetic average: $$\begin{array}{rcl}\sigma_{ij}&=&\frac{1}{2}\left(\sigma_{ii}+\sigma_{jj}\right)\\ \epsilon_{ij}&=&\left(\epsilon_{ii}\epsilon_{jj}\right)^{1/2}\end{array}$$
Default: 2

lj_eshift#

Type: Boolean
Description: It True, the LJ potential is shifted by a constant such that it is zero at the cut-off distance.
Default: False

lj_rcut#

Type: Real
Description: Cut-off radius for Leonard Jones potential, beyond which the interaction will be neglected. It can be a single value, which means that all pairs of atoms types share the same cut-off radius. Otherwise, it should be a multiple-component vector, containing $N(N+1)/2$ values, see details in lj_rule.
Default: No default
Unit: Angstrom

lj_epsilon#

Type: Real
Description: The vector representing the $\epsilon$ matrix for Leonard Jones potential. See details in lj_rule.
Default: No default
Unit: eV

lj_sigma#

Type: Real
Description: The vector representing the $\sigma$ matrix for Leonard Jones potential. See details in lj_rule.
Default: No default
Unit: Angstrom

pot_file#

Type: String
Description: The filename of DP potential files, see md.md in detail.
Default: graph.pb

dp_rescaling#

Type: Real
Availability: esolver_type = dp.
Description: Rescaling factor to use a temperature-dependent DP. Energy, stress and force calculated by DP will be multiplied by this factor.
Default: 1.0

dp_fparam#

Type: Real
Availability: esolver_type = dp.
Description: The frame parameter for dp potential. The array size is dim_fparam, then all frames are assumed to be provided with the same fparam.
Default: {}

dp_aparam#

Type: Real
Availability: esolver_type = dp.
Description: The atomic parameter for dp potential. The array size can be (1) natoms x dim_aparam, then all frames are assumed to be provided with the same aparam; (2) dim_aparam, then all frames and atoms are assumed to be provided with the same aparam.
Default: {}

msst_direction#

Type: Integer
Description: The direction of the shock wave in the MSST method.
- 0: x direction
- 1: y direction
- 2: z direction
Default: 2

msst_vel#

Type: Real
Description: The velocity of the shock wave in the MSST method.
Default: 0.0
Unit: Angstrom/fs

msst_vis#

Type: Real
Description: Artificial viscosity in the MSST method.
Default: 0.0
Unit: g/(mol*Angstrom*fs)

msst_tscale#

Type: Real
Description: The reduction percentage of the initial temperature used to compress volume in the MSST method.
Default: 0.01

msst_qmass#

Type: Real
Description: Inertia of the extended system variable. You should set a number larger than 0.
Default: No default
Unit: $\mathrm{g^{2}/(mol^{2}*Angstrom^{4})}$

md_damp#

Type: Real
Description: The damping parameter used to add fictitious force in the Langevin method.
Default: 1.0
Unit: fs

md_tolerance#

Type: Real
Description: Thr temperature tolerance for velocity rescaling. Velocities are rescaled if the current and target temperature differ more than md_tolerance.
Default: 100.0
Unit: K

md_nraise#

Type: Integer
Description:
- Anderson: The “collision frequency” parameter is given as 1/md_nraise.
- Berendsen: The “rise time” parameter is given in units of the time step: tau = md_nraise*md_dt, so md_dt/tau = 1/md_nraise.
- Rescale_v: Every md_nraise steps the current temperature is rescaled to the target temperature.
Default: 1

cal_syns#

Type: Boolean
Description: Whether the asynchronous overlap matrix is calculated for Hefei-NAMD.
Default: False

dmax#

Type: Real
Description: The maximum displacement of all atoms in one step. This parameter is useful when cal_syns = True.
Default: 0.01
Unit: bohr

DFT+U correction#

These variables are used to control DFT+U correlated parameters

dft_plus_u#

Type: Integer
Description: Determines whether to calculate the plus U correction, which is especially important for correlated electrons.
- 1: Calculate plus U correction with radius-adjustable localized projections (with parameter onsite_radius).
- 2: Calculate plus U correction using first zeta of NAOs as projections (this is old method for testing).
- 0: Do not calculate plus U correction.
Default: 0

orbital_corr#

Type: Integer
Description: Specifies which orbits need plus U correction for each atom type ($l_1,l_2,l_3,\ldots$ for atom type 1, 2, 3, respectively).
- -1: The plus U correction will not be calculated for this atom.
- 1: For p-electron orbits, the plus U correction is needed.
- 2: For d-electron orbits, the plus U correction is needed.
- 3: For f-electron orbits, the plus U correction is needed.
Default: -1

hubbard_u#

Type: Real
Description: Specifies the Hubbard Coulomb interaction parameter U (eV) in plus U correction, which should be specified for each atom unless the Yukawa potential is used.

Note: Since only the simplified scheme by Duradev is implemented, the ‘U’ here is actually U-effective, which is given by Hubbard U minus Hund J.

Default: 0.0

yukawa_potential#

Type: Boolean
Description: Determines whether to use the local screen Coulomb potential method to calculate the values of U and J.
- True: hubbard_u does not need to be specified.
- False: hubbard_u does need to be specified.
Default: False

yukawa_lambda#

Type: Real
Availability: DFT+U with yukawa_potential = True.
Description: The screen length of Yukawa potential. If left to default, the screen length will be calculated as an average of the entire system. It’s better to stick to the default setting unless there is a very good reason.
Default: Calculated on the fly.

uramping#

Type: Real
Unit: eV
Availability: DFT+U calculations with mixing_restart > 0.
Description: Once uramping > 0.15 eV. DFT+U calculations will start SCF with U = 0 eV, namely normal LDA/PBE calculations. Once SCF restarts when drho<mixing_restart, U value will increase by uramping eV. SCF will repeat above calcuations until U values reach target defined in hubbard_u. As for uramping=1.0 eV, the recommendations of mixing_restart is around 5e-4.
Default: -1.0.

omc#

Type: Integer
Description: The parameter controls the form of occupation matrix control used.
- 0: No occupation matrix control is performed, and the onsite density matrix will be calculated from wavefunctions in each SCF step.
- 1: The first SCF step will use an initial density matrix read from a file named [initial_onsite.dm](http://initial_onsite.dm/), but for later steps, the onsite density matrix will be updated.
- 2: The same onsite density matrix from initial_onsite.dm will be used throughout the entire calculation.

Note : The easiest way to create initial_onsite.dm is to run a DFT+U calculation, look for a file named onsite.dm in the OUT.prefix directory, and make replacements there. The format of the file is rather straight-forward.

Default: 0

onsite_radius#

Type: Real
Availability: dft_plus_u is set to 1
Description:
- The Onsite-radius parameter facilitates modulation of the single-zeta portion of numerical atomic orbitals for projections for DFT+U.
- The modulation algorithm includes a smooth truncation applied directly to the tail of the original orbital, followed by normalization. Consider the function: $$ g(r;\sigma)=\begin{cases} 1-\exp\left(-\frac{(r-r_c)^2}{2\sigma^2}\right), & r < r_c\\ 0, & r \geq r_c \end{cases} $$
- where $\sigma$ is a parameter that controls the smoothing interval. A normalized function truncated smoothly at $r_c$ can be represented as:
\[ \alpha(r) = \frac{\chi(r)g(r;\sigma)}{\langle\chi(r)g(r;\sigma), \chi(r)g(r;\sigma)\rangle} \]
- To find an appropriate $\sigma$, the optimization process is as follows:
- Maximizing the overlap integral under a normalization constraint is equivalent to minimizing an error function:
\[ \min \langle \chi(r)-\alpha(r), \chi(r)-\alpha(r)\rangle \quad \text{subject to} \quad \langle \alpha(r),\alpha(r)\rangle=1 \]
- Similar to the process of generating numerical atomic orbitals, this optimization choice often induces additional oscillations in the outcome. To suppress these oscillations, we may include a derivative term in the objective function ($f'(r)\equiv \mathrm{d}f(r)/\mathrm{d}r$):
\[ \min \left[\gamma\langle \chi(r)-\alpha(r), \chi(r)-\alpha(r)\rangle + \langle \chi'(r)-\alpha'(r), \chi'(r)-\alpha'(r)\rangle\right] \quad \text{subject to} \quad \langle \alpha(r),\alpha(r)\rangle=1 \]
- where $\gamma$ is a parameter that adjusts the relative weight of the error function to the derivative error function.
Unit: Bohr
Default: 3.0

vdW correction#

These variables are used to control vdW-corrected related parameters.

vdw_method#

Type: String
Description: Specifies the method used for Van der Waals (VdW) correction. Available options are:
- d2: Grimme’s D2 dispersion correction method
- d3_0: Grimme’s DFT-D3(0) dispersion correction method (zero-damping)
- d3_bj: Grimme’s DFTD3(BJ) dispersion correction method (BJ-damping)
- none: no vdW correction
Default: none
Note: ABACUS supports automatic setting on DFT-D3 parameters for common functionals after version 3.8.3 (and several develop versions earlier). To benefit from this feature, please specify the parameter dft_functional explicitly (for more details on this parameter, please see dft_functional), otherwise the autoset procedure will crash with error message like cannot find DFT-D3 parameter for XC(***). If not satisfied with those in-built parameters, any manually setting on vdw_s6, vdw_s8, vdw_a1 and vdw_a2 will overwrite.
Special: There are special cases for functional family wB97 (Omega-B97): if want to use the functional wB97X-D3BJ, one needs to specify the dft_functional as HYB_GGA_WB97X_V and vdw_method as d3_bj. If want to use the functional wB97X-D3, specify dft_functional as HYB_GGA_WB97X_D3 and vdw_method as d3_0.

vdw_s6#

Type: Real
Availability: vdw_method is set to d2, d3_0, or d3_bj
Description: This scale factor is used to optimize the interaction energy deviations in van der Waals (vdW) corrected calculations. The recommended values of this parameter are dependent on the chosen vdW correction method and the DFT functional being used. For DFT-D2, the recommended values are 0.75 (PBE), 1.2 (BLYP), 1.05 (B-P86), 1.0 (TPSS), and 1.05 (B3LYP). If not set, will use values of PBE functional. For DFT-D3, recommended values with different DFT functionals can be found on the here. If not set, will search in ABACUS built-in dataset based on the dft_functional keywords. User set value will overwrite the searched value.
Default:
- 0.75: if vdw_method is set to d2

vdw_s8#

Type: Real
Availability: vdw_method is set to d3_0 or d3_bj
Description: This scale factor is relevant for D3(0) and D3(BJ) van der Waals (vdW) correction methods. The recommended values of this parameter with different DFT functionals can be found on the webpage. If not set, will search in ABACUS built-in dataset based on the dft_functional keywords. User set value will overwrite the searched value.

vdw_a1#

Type: Real
Availability: vdw_method is set to d3_0 or d3_bj
Description: This damping function parameter is relevant for D3(0) and D3(BJ) van der Waals (vdW) correction methods. The recommended values of this parameter with different DFT functionals can be found on the webpage. If not set, will search in ABACUS built-in dataset based on the dft_functional keywords. User set value will overwrite the searched value.

vdw_a2#

Type: Real
Availability: vdw_method is set to d3_0 or d3_bj
Description: This damping function parameter is only relevant for D3(0) and D3(BJ) van der Waals (vdW) correction methods. The recommended values of this parameter with different DFT functionals can be found on the webpage. If not set, will search in ABACUS built-in dataset based on the dft_functional keywords. User set value will overwrite the searched value.

vdw_d#

Type: Real
Availability: vdw_method is set to d2
Description: Controls the damping rate of the damping function in the DFT-D2 method.
Default: 20

vdw_abc#

Type: Integer
Availability: vdw_method is set to d3_0 or d3_bj
Description: Determines whether three-body terms are calculated for DFT-D3 methods.
- True: ABACUS will calculate the three-body term.
- False: The three-body term is not included.
Default: False

vdw_C6_file#

Type: String
Availability: vdw_method is set to d2
Description: Specifies the name of the file containing $C_6$ parameters for each element when using the D2 method. If not set, ABACUS uses the default $C_6$ parameters (Jnm6/mol) stored in the program. To manually set the $C_6$ parameters, provide a file containing the parameters. An example is given by:
```
H  0.1
Si 9.0
```
Namely, each line contains the element name and the corresponding $C_6$ parameter.
Default: default

vdw_C6_unit#

Type: String
Availability: vdw_C6_file is not default
Description: Specifies the unit of the provided $C_6$ parameters in the D2 method. Available options are:
- Jnm6/mol (J·nm^6/mol)
- eVA (eV·Angstrom)
Default: Jnm6/mol

vdw_R0_file#

Type: String
Availability: vdw_method is set to d2
Description: Specifies the name of the file containing $R_0$ parameters for each element when using the D2 method. If not set, ABACUS uses the default $R_0$ parameters (Angstrom) stored in the program. To manually set the $R_0$ parameters, provide a file containing the parameters. An example is given by:
```
Li 1.0
Cl 2.0
```
Namely, each line contains the element name and the corresponding $R_0$ parameter.
Default: default

vdw_R0_unit#

Type: String
Availability: vdw_R0_file is not default
Description: Specifies the unit for the $R_0$ parameters in the D2 method when manually set by the user. Available options are:
- A (Angstrom)
- Bohr
Default: A

vdw_cutoff_type#

Type: String
Description: Determines the method used for specifying the cutoff radius in periodic systems when applying Van der Waals correction. Available options are:
- radius: The supercell is selected within a sphere centered at the origin with a radius defined by vdw_cutoff_radius.
- period: The extent of the supercell is explicitly specified using the vdw_cutoff_period keyword.
Default: radius

vdw_cutoff_radius#

Type: Real
Availability: vdw_cutoff_type is set to radius
Description: Defines the radius of the cutoff sphere when vdw_cutoff_type is set to radius. The default values depend on the chosen vdw_method.
Default:
- 56.6918 if vdw_method is set to d2
- 95 if vdw_method is set to d3_0 or d3_bj
Unit: defined by vdw_radius_unit (default Bohr)

vdw_radius_unit#

Type: String
Availability: vdw_cutoff_type is set to radius
Description: specify the unit of vdw_cutoff_radius. Available options are:
- A(Angstrom)
- Bohr
Default: Bohr

vdw_cutoff_period#

Type: Integer Integer Integer
Availability: vdw_cutoff_type is set to period
Description: The three integers supplied here explicitly specify the extent of the supercell in the directions of the three basis lattice vectors.
Default: 3 3 3

vdw_cn_thr#

Type: Real
Availability: vdw_method is set to d3_0 or d3_bj
Description: The cutoff radius when calculating coordination numbers.
Default: 40
Unit: defined by vdw_cn_thr_unit (default: Bohr)

vdw_cn_thr_unit#

Type: String
Description: Unit of the coordination number cutoff (vdw_cn_thr). Available options are:
- A(Angstrom)
- Bohr
Default: Bohr

Berry phase and wannier90 interface#

These variables are used to control berry phase and wannier90 interface parameters. Detail introduce

berry_phase#

Type: Boolean
Description: controls the calculation of Berry phase
- true: Calculate Berry phase.
- false: Do not calculate Berry phase.
Default: false

gdir#

Type: Integer
Description: the direction of the polarization in the lattice vector for Berry phase calculation
- 1: Calculate the polarization in the direction of the lattice vector a_1 defined in the STRU file.
- 2: Calculate the polarization in the direction of the lattice vector a_2 defined in the STRU file.
- 3: Calculate the polarization in the direction of the lattice vector a_3 defined in the STRU file.
Default: 3

towannier90#

Type: Integer
Description: Controls the generation of files for the Wannier90 code.
- 1: Generate files for the Wannier90 code.
- 0: Do not generate files for the Wannier90 code.
Default: 0

nnkpfile#

Type: String
Description: the file name generated when running “wannier90 -pp …” command
Default: seedname.nnkp

wannier_method#

Type: Integer
Description: Only available on LCAO basis, using different methods to generate “*.mmn” file and “*.amn” file.
- 1: Calculated using the lcao_in_pw method, the calculation accuracy can be improved by increasing ecutwfc to maintain consistency with the pw basis set results.
- 2: The overlap between atomic orbitals is calculated using grid integration. The radial grid points are generated using the Gauss-Legendre method, while the spherical grid points are generated using the Lebedev-Laikov method.
Default: 1

wannier_spin#

Type: String
Description: the spin direction for the Wannier function calculation when nspin is set to 2
- up: Calculate spin up for the Wannier function.
- down: Calculate spin down for the Wannier function.
Default: up

out_wannier_mmn#

Type: Bool
Description: write the “*.mmn” file or not.
- 0: don’t write the “*.mmn” file.
- 1: write the “*.mmn” file.
Default: 1

out_wannier_amn#

Type: Bool
Description: write the “*.amn” file or not.
- 0: don’t write the “*.amn” file.
- 1: write the “*.amn” file.
Default: 1

out_wannier_eig#

Type: Bool
Description: write the “*.eig” file or not.
- 0: don’t write the “*.eig” file.
- 1: write the “*.eig” file.
Default: 1

out_wannier_unk#

Type: Bool
Description: write the “UNK.*” file or not.
- 0: don’t write the “UNK.*” file.
- 1: write the “UNK.*” file.
Default: 0

out_wannier_wvfn_formatted#

Type: Bool
Description: write the “UNK.*” file in ASCII format or binary format.
- 0: write the “UNK.*” file in binary format.
- 1: write the “UNK.*” file in ASCII format (text file format).
Default: 1

TDDFT: time dependent density functional theory#

td_edm#

Type: Integer
Description: the method to calculate the energy density matrix
- 0: new method (use the original formula).
- 1: old method (use the formula for ground state).
Default: 0

td_print_eij#

Type: Real
Description:
- <0: don’t print $E_{ij}$.
- >=0: print the $E_{ij}\ (<\psi_i|H|\psi_j>$) elements which are larger than td_print_eij.
Default: -1

td_propagator#

Type: Integer
Description: method of propagator
- 0: Crank-Nicolson.
- 1: 4th Taylor expansions of exponential.
- 2: enforced time-reversal symmetry (ETRS).
Default: 0

td_vext#

Type: Boolean
Description:
- True: add a laser material interaction (extern laser field).
- False: no extern laser field.
Default: False

td_vext_dire#

Type: String
Description: If td_vext is True, the td_vext_dire is a string to set the number of electric fields, like td_vext_dire 1 2 representing external electric field is added to the x and y axis at the same time. Parameters of electric field can also be written as a string, like td_gauss_phase 0 1.5707963267948966 representing the Gauss field in the x and y directions has a phase delay of Pi/2. See below for more parameters of electric field.
- 1: the direction of external light field is along x axis.
- 2: the direction of external light field is along y axis.
- 3: the direction of external light field is along z axis.
Default: 1

td_stype#

Type: Integer
Description: type of electric field in space domain
- 0: length gauge.
- 1: velocity gauge.
Default: 0

td_ttype#

Type: Integer
Description: type of electric field in time domain
- 0: Gaussian type function.
- 1: Trapezoid function.
- 2: Trigonometric function.
- 3: Heaviside function.
- 4: HHG function.
Default: 0

td_tstart#

Type: Integer
Description: number of steps where electric field starts
Default: 1

td_tend#

Type: Integer
Description: number of steps where electric field ends
Default: 100

td_lcut1#

Type: Real
Description: cut1 of interval in length gauge
E = E0 , cut1<x<cut2
E = -E0/(cut1+1-cut2) , x<cut1 or cut2<x<1
Default: 0.05

td_lcut2#

Type: Real
Description: cut2 of interval in length gauge
E = E0 , cut1<x<cut2
E = -E0/(cut1+1-cut2) , x<cut1 or cut2<x<1
Default: 0.05

td_gauss_freq#

Type: Real
Description: frequency (freq) of Gauss type electric field (fs^-1)
amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)
Default: 22.13

td_gauss_phase#

Type: Real
Description: phase of Gauss type electric field
amp*(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)
Default: 0.0

td_gauss_sigma#

Type: Real
Description: sigma of Gauss type electric field (fs)
amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)
Default: 30.0

td_gauss_t0#

Type: Real
Description: step number of time center (t0) of Gauss type electric field
amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)
Default: 100

td_gauss_amp#

Type: Real
Description: amplitude (amp) of Gauss type electric field (V/Angstrom)
amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)
Default: 0.25

td_trape_freq#

Type: Real
Description: frequency (freq) of Trapezoid type electric field (fs^-1)
E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
E = amp*cos(2pi*freq*t+phase) , t1<t<t2
E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
E = 0 , t>t3
Default: 1.60

td_trape_phase#

Type: Real
Description: phase of Trapezoid type electric field
E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
E = amp*cos(2pi*freq*t+phase) , t1<t<t2
E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
E = 0 , t>t3
Default: 0.0

td_trape_t1#

Type: Real
Description: step number of time interval 1 (t1) of Trapezoid type electric field
E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
E = amp*cos(2pi*freq*t+phase) , t1<t<t2
E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
E = 0 , t>t3
Default: 1875

td_trape_t2#

Type: Real
Description: step number of time interval 2 (t2) of Trapezoid type electric field
E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
E = amp*cos(2pi*freq*t+phase) , t1<t<t2
E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
E = 0 , t>t3
Default: 5625

td_trape_t3#

Type: Real
Description: step number of time interval 3 (t3) of Trapezoid type electric field
E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
E = amp*cos(2pi*freq*t+phase) , t1<t<t2
E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
E = 0 , t>t3
Default: 7500

td_trape_amp#

Type: Real
Description: amplitude (amp) of Trapezoid type electric field (V/Angstrom)
E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
E = amp*cos(2pi*freq*t+phase) , t1<t<t2
E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
E = 0 , t>t3
Default: 2.74

td_trigo_freq1#

Type: Real
Description: frequency 1 (freq1) of Trigonometric type electric field (fs^-1)
amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2
Default: 1.164656

td_trigo_freq2#

Type: Real
Description: frequency 2 (freq2) of Trigonometric type electric field (fs^-1)
amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2
Default: 0.029116

td_trigo_phase1#

Type:Real
Description: phase 1 (phase1) of Trigonometric type electric field
amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2
Default: 0.0

td_trigo_phase2#

Type: Real
Description: phase 2 (phase2) of Trigonometric type electric field
amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2
Default: 0.0

td_trigo_amp#

Type: Real
Description: amplitude (amp) of Trigonometric type electric field (V/Angstrom)
amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2
Default: 2.74

td_heavi_t0#

Type: Real
Description: step number of switch time (t0) of Heaviside type electric field
E = amp , t<t0
E = 0.0 , t>t0
Default: 100

td_heavi_amp#

Type: Real
Description: amplitude (amp) of Heaviside type electric field (V/Angstrom)
E = amp , t<t0
E = 0.0 , t>t0
Default: 2.74

out_dipole#

Type: Boolean
Description:
- True: output dipole.
- False: do not output dipole.
Default: False

out_current#

Type: Boolean
Description:output current in real time TDDFT simulations with the velocity gauge
- True: output current.
- False: do not output current.
Default: False

out_current_k#

Type: Boolean
Description:output tddft current for all k points.
- True: output tddft current for all k points.
- False: output current in total.
Default: False

out_efield#

Type: Boolean
Description: output TDDFT Efield or not(V/Angstrom)
- True: output efield.
- False: do not output efield.
Default: False

out_vecpot#

Type: Boolean
Description: output TDDFT Vector potential or not(a.u.)
- True: output Vector potential in file “OUT.suffix/At.dat”
- False: do not output Vector potential.
Default: False

init_vecpot_file#

Type: Boolean
Description: Init vector potential through file or not
- True: init vector potential from file “At.dat”.(a.u.) It consists of four columns, representing istep and vector potential on each direction.
- False: calculate vector potential by integral of Efield
Default: False

ocp#

Type: Boolean
Availability:
- For PW and LCAO codes. if set to 1, occupations of bands will be setting of “ocp_set”.
- For TDDFT in LCAO codes. if set to 1, occupations will be constrained since second ionic step.
- For OFDFT, this feature can’t be used.
Description:
True: fix the occupations of bands.
False: do not fix the occupations of bands.
Default: False

ocp_set#

Type: String
Description: If ocp is True, the ocp_set is a string to set the number of occupancy, like ‘1 10 * 1 0 1’ representing the 13 band occupancy, 12th band occupancy 0 and the rest 1, the code is parsing this string into an array through a regular expression.
Default: none

Variables useful for debugging#

t_in_h#

Type: Boolean
Description: Specify whether to include kinetic term in obtaining the Hamiltonian matrix.
- 0: No.
- 1: Yes.
Default: 1

vl_in_h#

Type: Boolean
Description: Specify whether to include local pseudopotential term in obtaining the Hamiltonian matrix.
- 0: No.
- 1: Yes.
Default: 1

vnl_in_h#

Type: Boolean
Description: Specify whether to include non-local pseudopotential term in obtaining the Hamiltonian matrix.
- 0: No.
- 1: Yes.
Default: 1

vh_in_h#

Type: Boolean
Description: Specify whether to include Hartree potential term in obtaining the Hamiltonian matrix.
- 0: No.
- 1: Yes.
Default: 1

vion_in_h#

Type: Boolean
Description: Specify whether to include local ionic potential term in obtaining the Hamiltonian matrix.
- 0: No.
- 1: Yes.
Default: 1

test_force#

Type: Boolean
Description: Specify whether to output the detailed components in forces.
- 0: No.
- 1: Yes.
Default: 0

test_stress#

Type: Boolean
Description: Specify whether to output the detailed components in stress.
- 0: No.
- 1: Yes.
Default: 0
Type: Boolean
Description: Specify whether to set the colorful output in terminal.
- 0: No.
- 1: Yes.
Default: 0

test_skip_ewald#

Type: Boolean
Description: Specify whether to skip the calculation of the ewald energy.
- 0: No.
- 1: Yes.
Default: 0

Electronic conductivities#

Frequency-dependent electronic conductivities can be calculated with Kubo-Greenwood formula [Phys. Rev. B 83, 235120 (2011)].

Onsager coefficients:

$L_{mn}(\omega)=(-1)^{m+n}\frac{2\pi e^2\hbar^2}{3m_e^2\omega\Omega}$

$\times\sum_{ij\alpha\mathbf{k}}W(\mathbf{k})\left(\frac{\epsilon_{i\mathbf{k}}+\epsilon_{j\mathbf{k}}}{2}-\mu\right)^{m+n-2} \times |\langle\Psi_{i\mathbf{k}}|\nabla_\alpha|\Psi_{j\mathbf{k}}\rangle|^2$

$\times[f(\epsilon_{i\mathbf{k}})-f(\epsilon_{j\mathbf{k}})]\delta(\epsilon_{j\mathbf{k}}-\epsilon_{i\mathbf{k}}-\hbar\omega).$

They can also be computed by $j$-$j$ correlation function.

$L_{mn}=\frac{2e^{m+n-2}}{3\Omega\hbar\omega}\Im[\tilde{C}_{mn}(\omega)]$ Guassian smearing: $\tilde{C}_{mn}=\int_0^\infty C_{mn}(t)e^{-i\omega t}e^{-\frac{1}{2}s^2t^2}dt$ Lorentzian smearing: $\tilde{C}_{mn}=\int_0^\infty C_{mn}(t)e^{-i\omega t}e^{-\gamma t}dt$

$C_{mn}(t)=-2\theta(t)\Im\left\{Tr\left[\sqrt{\hat f}\hat{j}_m(1-\hat{f})e^{i\frac{\hat{H}}{\hbar}t}\hat{j}_ne^{-i\frac{\hat{H}}{\hbar}t}\sqrt{\hat f}\right]\right\}$,

where $j_1$ is electric flux and $j_2$ is thermal flux.

Frequency-dependent electric conductivities: $\sigma(\omega)=L_{11}(\omega)$.

Frequency-dependent thermal conductivities: $\kappa(\omega)=\frac{1}{e^2T}\left(L_{22}-\frac{L_{12}^2}{L_{11}}\right)$.

DC electric conductivities: $\sigma = \lim_{\omega\to 0}\sigma(\omega)$.

Thermal conductivities: $\kappa = \lim_{\omega\to 0}\kappa(\omega)$.

cal_cond#

Type: Boolean
Availability: basis_type = pw
Description: Whether to calculate electronic conductivities.
Default: False

cond_che_thr#

Type: Real
Availability: esolver_type = sdft
Description: Control the error of Chebyshev expansions for conductivities.
Default: 1e-8

cond_dw#

Type: Real
Availability: basis_type = pw
Description: Frequency interval ($\mathrm{d}\omega$) for frequency-dependent conductivities.
Default: 0.1
Unit: eV

cond_wcut#

Type: Real
Availability: basis_type = pw
Description: Cutoff frequency for frequency-dependent conductivities.
Default: 10.0
Unit: eV

cond_dt#

Type: Real
Availability: basis_type = pw
Description: Time interval ($\mathrm{d}t$) to integrate Onsager coefficients.
Default: 0.02
Unit: a.u.

cond_dtbatch#

Type: Integer
Availability: esolver_type = sdft
Description: exp(iH*dt*cond_dtbatch) is expanded with Chebyshev expansion to calculate conductivities. It is faster but costs more memory.
- If cond_dtbatch = 0: Autoset this parameter to make expansion orders larger than 100.
Default: 0

cond_smear#

Type: Integer
Description: Smearing method for conductivities
- 1: Gaussian smearing
- 2: Lorentzian smearing
Default: 1

cond_fwhm#

Type: Real
Availability: basis_type = pw
Description: FWHM for conductivities. For Gaussian smearing, $\mathrm{FWHM}=2\sqrt{2\ln2}s$; for Lorentzian smearing, $\mathrm{FWHM}=2\gamma$.
Default: 0.4
Unit: eV

cond_nonlocal#

Type: Boolean
Availability: basis_type = pw
Description: Whether to consider nonlocal potential correction when calculating velocity matrix $\bra{\psi_i}\hat{v}\ket{\psi_j}$.
- True: $m\hat{v}=\hat{p}+\frac{im}{\hbar}[\hat{V}_{NL},\hat{r}]$.
- False: $m\hat{v}\approx\hat{p}$.
Default: True

Implicit solvation model#

These variables are used to control the usage of implicit solvation model. This approach treats the solvent as a continuous medium instead of individual “explicit” solvent molecules, which means that the solute is embedded in an implicit solvent and the average over the solvent degrees of freedom becomes implicit in the properties of the solvent bath.

imp_sol#

Type: Boolean
Description: calculate implicit solvation correction
Default: False

eb_k#

Type: Real
Availability: imp_sol is true.
Description: the relative permittivity of the bulk solvent, 80 for water
Default: 80

tau#

Type: Real
Description: The effective surface tension parameter that describes the cavitation, the dispersion, and the repulsion interaction between the solute and the solvent which are not captured by the electrostatic terms
Default: 1.0798e-05
Unit: $Ry/Bohr^{2}$

sigma_k#

Type: Real
Description: the width of the diffuse cavity that is implicitly determined by the electronic structure of the solute
Default: 0.6

nc_k#

Type: Real
Description: the value of the electron density at which the dielectric cavity forms
Default: 0.00037
Unit: $Bohr^{-3}$

Quasiatomic Orbital (QO) analysis#

These variables are used to control the usage of QO analysis. QO further compress information from LCAO: usually PW basis has dimension in million, LCAO basis has dimension below thousand, and QO basis has dimension below hundred.

qo_switch#

Type: Boolean
Description: whether to let ABACUS output QO analysis required files
Default: 0

qo_basis#

Type: String
Description: specify the type of atomic basis
- pswfc: use the pseudowavefunction in pseudopotential files as atomic basis. To use this option, please make sure in pseudopotential file there is pswfc in it.
- hydrogen: generate hydrogen-like atomic basis (or with Slater screening).
- szv: use the first set of zeta for each angular momentum from numerical atomic orbitals as atomic basis.
warning: to use pswfc , please use norm-conserving pseudopotentials with pseudowavefunctions, SG15 pseudopotentials cannot support this option. Developer notes: for ABACUS-lcao calculation, it is the most recommend to use szv instead of pswfc which is originally put forward in work of QO implementation on PW basis. The information loss always happens if pswfc or hydrogen orbitals are not well tuned, although making kpoints sampling more dense will mitigate this problem, but orbital-adjust parameters are needed to test system-by-system in this case.
Default: szv

qo_strategy#

Type: String [String…](optional)
Description: specify the strategy to generate radial orbitals for each atom type. If one parameter is given, will apply to all atom types. If more than one parameters are given but fewer than number of atom type, those unspecified atom type will use default value.

For qo_basis hydrogen
- minimal-nodeless: according to principle quantum number of the highest occupied state, generate only nodeless orbitals, for example Cu, only generate 1s, 2p, 3d and 4f orbitals (for Cu, 4s is occupied, thus $n_{max} = 4$)
- minimal-valence: according to principle quantum number of the highest occupied state, generate only orbitals with highest principle quantum number, for example Cu, only generate 4s, 4p, 4d and 4f orbitals.
- full: similarly according to the maximal principle quantum number, generate all possible orbitals, therefore for Cu, for example, will generate 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f.
- energy-full: will generate hydrogen-like orbitals according to Aufbau principle. For example the Cu (1s2 2s2 2p6 3s2 3p6 3d10 4s1), will generate these orbitals.
- energy-valence: from the highest n (principal quantum number) layer and n-1 layer, generate all occupied and possible ls (angular momentum quantum number) for only once, for example Cu, will generate 4s, 3d and 3p orbitals.
For qo_basis pswfc and qo_basis szv
- all: use all possible pseudowavefunctions/numerical atomic orbital (of first zeta) in pseudopotential/numerical atomic orbital file.
- s/p/d/…: only use s/p/d/f/…-orbital(s).
- spd: use s, p and d orbital(s). Any unordered combination is acceptable.
warning: for qo_basis hydrogen to use full, generation strategy may cause the space spanned larger than the one spanned by numerical atomic orbitals, in this case, must filter out orbitals in some way
Default: for hydrogen: energy-valence, for pswfc and szv: all

qo_screening_coeff#

Type: Real [Real…](optional)
Description: rescale the shape of radial orbitals, available for both qo_basis hydrogen and qo_basis pswfc. cases but has different meaning.

For qo_basis pswfc For each atom type, screening factor $e^{-\eta|\mathbf{r}|}$ is multiplied to the pswfc to mimic the behavior of some kind of electron. $\eta$ is the screening coefficient. If only one value is given, then will apply to each atom type. If not enough values are given, will apply default value to rest of atom types. This parameter plays important role in controlling the spread of QO orbitals together with qo_thr.

For qo_basis hydrogen If any float number is given, will apply Slater screening to all atom types. Slater screening is a classic and empirical method roughly taking many-electron effect into account for obtaining more accurate results when evaluating electron affinity and ionization energy. The Coulomb potential then becomes $V(r) = -\frac{Z-\sigma}{r}$. For example the effective nuclear charge for Cu 3d electrons now reduces from 29 to 7.85, 4s from 29 to 3.70, which means Slater screening will bring about longer tailing effect. If no value is given, will not apply Slater screening.
Default: 0.1
Unit: Bohr^-1

qo_thr#

Type: Real
Description: the convergence threshold determining the cutoff of generated orbital. Lower threshold will yield orbital with larger cutoff radius.
Default: 1.0e-6

PEXSI#

These variables are used to control the usage of PEXSI (Pole Expansion and Selected Inversion) method in calculations.

pexsi_npole#

Type: Integer
Description: the number of poles used in the pole expansion method, should be a even number.
Default: 40

pexsi_inertia#

Type: Boolean
Description: whether inertia counting is used at the very beginning.
Default: True

pexsi_nmax#

Type: Integer
Description: maximum number of PEXSI iterations after each inertia counting procedure.
Default: 80

pexsi_comm#

Type: Boolean
Description: whether to construct PSelInv communication pattern.
Default: True

pexsi_storage#

Type: Boolean
Description: whether to use symmetric storage space used by the Selected Inversion algorithm for symmetric matrices.
Default: True

pexsi_ordering#

Type: Integer
Description: ordering strategy for factorization and selected inversion. 0: Parallel ordering using ParMETIS, 1: Sequential ordering using METIS, 2: Multiple minimum degree ordering
Default: 0

pexsi_row_ordering#

Type: Integer
Description: row permutation strategy for factorization and selected inversion, 0: No row permutation, 1: Make the diagonal entry of the matrix larger than the off-diagonal entries.
Default: 1

pexsi_nproc#

Type: Integer
Description: number of processors for PARMETIS. Only used if pexsi_ordering == 0.
Default: 1

pexsi_symm#

Type: Boolean
Description: whether the matrix is symmetric.
Default: True

pexsi_trans#

Type: Boolean
Description: whether to factorize the transpose of the matrix.
Default: False

pexsi_method#

Type: Integer
Description: the pole expansion method to be used. 1 for Cauchy Contour Integral method, 2 for Moussa optimized method.
Default: 1

pexsi_nproc_pole#

Type: Integer
Description: the point parallelizaion of PEXSI. Recommend two points parallelization.
Default: 1

pexsi_temp#

Type: Real
Description: temperature in Fermi-Dirac distribution, in Ry, should have the same effect as the smearing sigma when smearing method is set to Fermi-Dirac.
Default: 0.015

pexsi_gap#

Type: Real
Description: spectral gap, this can be set to be 0 in most cases.
Default: 0

pexsi_delta_e#

Type: Real
Description: an upper bound for the spectral radius of $S^{-1} H$.
Default: 20

pexsi_mu_lower#

Type: Real
Description: initial guess of lower bound for mu.
Default: -10

pexsi_mu_upper#

Type: Real
Description: initial guess of upper bound for mu.
Default: 10

pexsi_mu#

Type: Real
Description: initial guess for mu (for the solver).
Default: 0

pexsi_mu_thr#

Type: Real
Description: stopping criterion in terms of the chemical potential for the inertia counting procedure.
Default: 0.05

pexsi_mu_expand#

Type: Real
Description: if the chemical potential is not in the initial interval, the interval is expanded by this value.
Default: 0.3

pexsi_mu_guard#

Type: Real
Description: safe guard criterion in terms of the chemical potential to reinvoke the inertia counting procedure.
Default: 0.2

pexsi_elec_thr#

Type: Real
Description: stopping criterion of the PEXSI iteration in terms of the number of electrons compared to numElectronExact.
Default: 0.001

pexsi_zero_thr#

Type: Real
Description: if the absolute value of CCS matrix element is less than this value, it will be considered as zero.
Default: 1e-10

Linear Response TDDFT#

These parameters are used to solve the excited states using. e.g. LR-TDDFT.

xc_kernel#

Type: String
Description: The exchange-correlation kernel used in the calculation. Currently supported: RPA, LDA, PBE, HSE, HF.
Default: LDA

lr_init_xc_kernel#

Type: String
Description: The method to initalize the xc kernel.
- “default”: Calculate xc kerenel ($f_\text{xc}$) from the ground-state charge density.
- “file”: Read the xc kernel $f_\text{xc}$ on grid from the provided files. The following words should be the paths of “.cube” files, where the first 1 (nspin==1) or 3 (nspin==2, namely spin-aa, spin-ab and spin-bb) will be read in. The parameter xc_kernel will be invalid. Now only LDA-type kernel is supproted as the potential will be calculated by directly multiplying the transition density.
- “from_charge_file”: Calculate fxc from the charge density read from the provided files. The following words should be the paths of “.cube” files, where the first nspin files will be read in.
Default: “default”

lr_solver#

Type: String
Description: The method to solve the Casida equation $AX=\Omega X$ in LR-TDDFT under Tamm-Dancoff approximation (TDA), where $A_{ai,bj}=(\epsilon_a-\epsilon_i)\delta_{ij}\delta_{ab}+(ai|f_{Hxc}|bj)+\alpha_{EX}(ab|ij)$ is the particle-hole excitation matrix and $X$ is the transition amplitude.
- dav/dav_subspace/ cg: Construct $AX$ and diagonalize the Hamiltonian matrix iteratively with Davidson/Non-ortho-Davidson/CG algorithm.
- lapack: Construct the full $A$ matrix and directly diagonalize with LAPACK.
- spectrum: Calculate absorption spectrum only without solving Casida equation. The OUT.${suffix}/ directory should contain the files for LR-TDDFT eigenstates and eigenvalues, i.e. Excitation_Energy.dat and Excitation_Amplitude_${processor_rank}.dat output by setting out_wfc_lr to true.
Default: dav

lr_thr#

Type: Real
Description: The convergence threshold of iterative diagonalization solver fo LR-TDDFT. It is a pure-math number with the same as pw_diag_thr, but since the Casida equation is a one-shot eigenvalue problem, it is also the convergence threshold of LR-TDDFT.
Default: 1e-2

nocc#

Type: Integer
Description: The number of occupied orbitals (up to HOMO) used in the LR-TDDFT calculation.
- Note: If the value is illegal ( > nelec/2 or <= 0), it will be autoset to nelec/2.
Default: nband

nvirt#

Type: Integer
Description: The number of virtual orbitals (staring from LUMO) used in the LR-TDDFT calculation.
Default: 1

lr_nstates#

Type: Integer
Description: The number of 2-particle states to be solved
Default: 0

lr_unrestricted#

Type: Boolean
Description: Whether to use unrestricted construction for LR-TDDFT (the matrix size will be doubled).
- True: Always use unrestricted LR-TDDFT.
- False: Use unrestricted LR-TDDFT only when the system is open-shell.
Default: False

abs_wavelen_range#

Type: Real Real
Description: The range of the wavelength for the absorption spectrum calculation.
Default: 0.0 0.0

out_wfc_lr#

Type: Boolean
Description: Whether to output the eigenstates (excitation energy) and eigenvectors (excitation amplitude) of the LR-TDDFT calculation. The output files are OUT.${suffix}/Excitation_Energy.dat and OUT.${suffix}/Excitation_Amplitude_${processor_rank}.dat.
Default: False

abs_broadening#

Type: Real
Description: The broadening factor $\eta$ for the absorption spectrum calculation.
Default: 0.01

ri_hartree_benchmark#

Type: String
Description: Whether to use the localized resolution-of-identity (LRI) approximation for the Hartree term of kernel in the $A$ matrix of LR-TDDFT for benchmark (with FHI-aims or another ABACUS calculation). Now it only supports molecular systems running with a single processor, and a large enough supercell should be used to make LRI C, V tensors contain only the R=(0 0 0) cell.
- aims: The OUT.${suffix}directory should contain the FHI-aims output files: RI-LVL tensorsCs_data_0.txt and coulomb_mat_0.txt, and KS eigenstates from FHI-aims: band_outand KS_eigenvectors.out. The Casida equation will be constructed under FHI-aims’ KS eigenpairs.
  - LRI tensor files (Cs_data_0.txt and coulomb_mat_0.txt)and Kohn-Sham eigenvalues (bands_out): run FHI-aims with periodic boundary conditions and with total_energy_method rpa and output librpa.
  - Kohn-Sham eigenstates under aims NAOs (KS_eigenvectors.out): run FHI-aims with output eigenvectors.
  - If the number of atomic orbitals of any atom type in FHI-aims is different from that in ABACUS, the aims_nbasis should be set.
- abacus: The OUT.${suffix}directory should contain the RI-LVL tensors Cs and Vs (written by setting out_ri_cv to 1). The Casida equation will be constructed under ABACUS’ KS eigenpairs, with the only difference that the Hartree term is constructed with RI approximation.
- none: Construct the Hartree term by Poisson equation and grid integration as usual.
Default: none

aims_nbasis#

Type: A number(ntype) of Integers
Availability: ri_hartree_benchmark = aims
Description: Atomic basis set size for each atom type (with the same order as in STRU) in FHI-aims.
Default: {} (empty list, where ABACUS use its own basis set size)

Reduced Density Matrix Functional Theory#

ab-initio methods and the xc-functional parameters used in RDMFT. The physical quantities that RDMFT temporarily expects to output are the kinetic energy, total energy, and 1-RDM of the system in the ground state, etc.

rdmft#

Type: Boolean
Description: Whether to perform rdmft calculation (reduced density matrix funcional theory)
Default: false

rdmft_power_alpha#

Type: Real
Description: The alpha parameter of power-functional(or other exx-type/hybrid functionals) which used in RDMFT, g(occ_number) = occ_number^alpha
Default: 0.656