# Phonopy

Phonopy (Note: please use the develop branch, rather than the master branch until the abacus interface has been merged into phonopy’s master branch.) is a powerful package to calculate phonon and related properties. It has provided interface with ABACUS. In the following, we take the FCC aluminum as an example:

1. Prepare a ‘setting.conf’ with following tags:

DIM=2 2 2
ATOM_NAME = Al

• when three integers are specified after DIM =, a supercell elongated along axes of unit cell is created

• chemical symbols are specified after ATOM_NAME =, number of symbols should match ntype in ABACUS INPUT file

1. To obtain supercells ($$2\times 2\times 2$$) with displacements, run phonopy:

phonopy setting.conf --abacus -d

1. Calculate forces on atoms in the supercells with displacements. For each SCF calculation, you should specify stru_file with STRU-{number} and cal_force=1 in INPUT in order to calculate force using ABACUS. Be careful not to relax the structures

echo 'stru_file ./STRU-001' >> INPUT

1. Then create ‘FORCE_SETS’ file using ABACUS inteface:

phonopy -f ./disp-{number}/OUT*/running*.log

1. Calculate the phonon dispersion:

phonopy band.conf --abacus


using the following band.conf file:

ATOM_NAME = Al
DIM = 2 2 2
MESH = 8 8 8
PRIMITIVE_AXES = 0 1/2 1/2  1/2 0 1/2  1/2 1/2 0
BAND= 1 1 1  1/2 1/2 1  3/8 3/8 3/4  0 0 0   1/2 1/2 1/2
BAND_POINTS = 21
BAND_CONNECTION = .TRUE.