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]