Interfaces to calculators

Currently the built-in interfaces for VASP, Pwscf, and CRYSTAL are prepared. VASP is the default interface and no special option is necessary to invoke it, but for the other interfaces, each special option has to be specified, e.g. --pwscf, --crystal, or --abinit.

Calculator specific behaviors

Physical unit

The interfaces for VASP, Pwscf, CRYSTAL, and Abinit are built in to the phono3py command.

For each calculator, each physical unit system is used. The physical unit systems used for the calculators are summarized below.

        | unit-cell  FORCES_FC3   disp_fc3.yaml
-----------------------------------------------
VASP    | Angstrom   eV/Angstrom  Angstrom
Pwscf   | au (bohr)  Ry/au        au
CRYSTAL | Angstrom   eV/Angstrom  Angstrom
Abinit  | au (bohr)  eV/Angstrom  au

FORCES_FC2 and disp_fc2.yaml have the same physical units as FORCES_FC3 and disp_fc3.yaml, respectively.

Always (irrespective of calculator interface) the physical units of 2nd and 3rd order force constants that are to be stored in fc2.hdf5 and fc3.hdf5 are eV/Angstrom^2 and eV/Angstrom^3, respectively.

Default unit cell file name

Default unit cell file names are also changed according to the calculators:

VASP    | POSCAR
Pwscf   | unitcell.in
CRYSTAL | crystal.o
Abinit  | unitcell.in

Default displacement distance created

Default displacement distances created by -d option without --amplitude option are respectively as follows:

VASP    | 0.03 Angstrom
Pwscf   | 0.06 au (bohr)
CRYSTAL | 0.03 Angstrom
Abinit  | 0.06 au (bohr)