Extracting Wave Functions#
ABACUS is able to output electron wave functions in both PW and LCAO basis calculations. One can find the examples in examples/11_wfc.
Wave Function in G-Space#
For basis_type=pw and esolver_type=ksdft, out_wfc_pw controls the output of plane-wave Kohn-Sham coefficients:
0: Do not write wave-function coefficients.1: Write text files with the.txtsuffix.2: Write binary files with the.datsuffix.
The files are stored in OUT.${suffix}/. Their pattern is wfk{k}[s{spin}][g{geometry step}][e{electronic iteration}]_pw.txt for out_wfc_pw=1 and wfk{k}[s{spin}][g{geometry step}][e{electronic iteration}]_pw.dat for out_wfc_pw=2. The s* label is omitted for nspin=1, is s1 or s2 for nspin=2, and is s4 for nspin=4. All PW files include the k* label, including Gamma-only calculations.
With out_freq_ion=0, files are written only when the electronic calculation converges or reaches scf_nmax; no g* or e* index is added. During structural relaxation or molecular dynamics with out_app_flag=1, the first written step truncates the unindexed files and later ionic steps append one frame per step; with out_app_flag=0 (the default) the unindexed files are overwritten at every write. With out_freq_ion>0, output is restricted to the ionic steps selected by out_freq_ion. For out_app_flag=0 or 2, output occurs at multiples of out_freq_elec, at convergence, or at scf_nmax; for out_app_flag=1 only the last electronic iteration of each selected ionic step is written (out_freq_elec is ignored), so the appended file holds exactly one frame per step. Both g* and e* indices are then added only when out_app_flag=2; with out_app_flag=0 the fixed files are truncated and overwritten at every write, and with out_app_flag=1 they accumulate one frame per written step.
The init_wfc file binary path reads only unindexed binary wf*_pw.dat files from read_file_dir, starting from the first frame. Such directly reusable files are normally generated with out_wfc_pw=2 and out_freq_ion=0; multi-frame files accumulated under out_app_flag=1 are trajectories and only their first frame is visible to the reader. Text wf*_pw.txt files and files containing g* or e* indices are not matched automatically.
For basis_type=lcao, out_wfc_lcao controls the output of numerical-atomic-orbital coefficients: 1 writes text files with the .txt suffix and 2 writes binary files with the .dat suffix. Multi-k calculations generate wfs{spin}k{k-point}_nao.txt or .dat, while Gamma-only calculations generate wfs{spin}_nao.txt or .dat.
To reuse LCAO coefficients, point read_file_dir to the coefficient files and set init_wfc file txt for text input or init_wfc file binary for binary input. The selected extension is required; there is no automatic format fallback. Only independent files without geometry-step indices are supported, not files accumulated with out_app_flag=1.
Wave Function in Real Space#
One can also choose to output real-space wave functions with the keyword out_wfc_norm or out_wfc_re_im.
Notice: When the basis_type is lcao, only get_wf calculation is effective. An example is examples/11_wfc/lcao_ienvelope_Si2.