phonopy/example/NaCl-QE/README.md

This is an example of QE-PW interface.

To create supercells with displacements:

% phonopy --qe -c NaCl.in -d --dim 2 2 2 --pa auto

A perfect 2x2x2 supercell (supercell.in) and two 2x2x2 supercells (supercell-xxx.in) of the conventional unit cell written in NaCl.in are created. In addition, phonopy_disp.yaml file is created. After force calculations with the crystal structures in supercell-xxx.in, it is needed to create FORCE_SETS file by

% phonopy -f NaCl-001.out NaCl-002.out

Here *.out files are the output of the PW calculations and are supposed to contain the forces on atoms calculated by PW. The phonopy_disp.yaml file has to be put in the current directory. Now you can run phonon calculation, e.g.,

% phonopy-load --band "0.0 0.0 0.0  0.5 0.0 0.0  0.5 0.5 0.0  0.0 0.0 0.0  0.5 0.5 0.5" -p

BORN file is created running DFPT calculation using ph.x (phonon) code in the quantum espresso package. The details are found in the phonopy documentation. The input and output files of the ph.x DFPT calculation are NaCl.ph.in and NaCl.ph.out.

Thermal properties at constant volume are calculated by setting regular grid with --mesh and -t option:

% phonopy-load -t --mesh 31 31 31

The thermal properties are written in thermal_properties.yaml.