Abinit & phonopy calculation#

Supported Abinit variables#

Currently Abinit variables that phonopy can read are shown below. More variables may be supported on request.

acell, natom, ntypat, rprim, scalecart, typat, xangst, xcart, xred, znucl

A procedure of Abinit-phonopy calculation is as follows:

Read an Abinit main input file and create supercells with --abinit option:
```
% phonopy --abinit -d --dim="2 2 2" -c NaCl.in
```
In this example, 2x2x2 supercells are created. supercell.in and supercell-xxx.in (xxx are numbers) give the perfect supercell and supercells with displacements, respectively. In these supercell files, lines only related to crystal structures are generated. phonopy_disp.yaml is also created. This file contains information on displacements. Perhaps the supercell files are stored in disp-xxx directories, then Abinit calculations are executed in these directories.
Calculate forces on atoms in the supercells with displacements. Calculation specification variables have to be added to supercell-xxx.in files. Crystal structure is not allowed to relaxed in the force calculations, because atomic forces induced by a small atomic displacement are what we need for phonon calculation.
Create FORCE_SETS by
```
% phonopy -f disp-001/supercell-001.out disp-002/supercell-002.out  ...
```
To run this command, phonopy_disp.yaml has to be located in the current directory because the atomic displacements are written into the FORCE_SETS file. See some more detail at ABINIT interface. An example is found in example/NaCl-abinit.

Run post-process of phonopy with the Abinit main input file for the unit cell used in the step 1:

% phonopy --abinit -c NaCl.in -p band.conf

or:

% phonopy --abinit -c NaCl.in --dim="2 2 2" [other-OPTIONS] [setting-file]