phonopy/doc/interfaces.md

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(calculator_interfaces)=
# Interfaces to calculators
The interfaces for VASP, WIEN2k, Quantum ESPRESSO (QE), ABINIT, Elk, SIESTA,
CRYSTAL, DFTB+, TURBOMOLE, FHI-AIMS, CASTEP, ABACUS, and LAMMPS are built in to
the usual phonopy command. See the command options and how to invoke each of
them at {ref}`force_calculators`. {ref}`LAMMPS interface
<external_tools_phonolammps>` is provided as an external tool by Abel Carreras.
(interfaces_to_force_calculators)=
## List of force calculators
Short tutorials for the force calculators are found in the following pages.
```{toctree}
:maxdepth: 1
vasp
wien2k
qe
abinit
siesta
elk
crystal
dftb+
turbomole
cp2k
aims
castep
Fleur
abacus
lammps
```
The VASP DFPT interface reads `vasprun.xml` and creates `FORCE_CONSTANTS` file.
```{toctree}
:maxdepth: 1
vasp-dfpt
```
(interfaces-physical-units)=
## Physical unit system for calculator
Physical unit systems used for the calculators are as follows:
```
| Distance Atomic mass Force Force constants
-----------------------------------------------------------------
VASP | Angstrom AMU eV/Angstrom eV/Angstrom^2
WIEN2k | au (bohr) AMU mRy/au mRy/au^2
QE | au (bohr) AMU Ry/au Ry/au^2
ABINIT | au (bohr) AMU eV/Angstrom eV/Angstrom.au
SIESTA | au (bohr) AMU eV/Angstrom eV/Angstrom.au
Elk | au (bohr) AMU hartree/au hartree/au^2
CRYSTAL | Angstrom AMU eV/Angstrom eV/Angstrom^2
TURBOMOLE | au (bohr) AMU hartree/au hartree/au^2
CP2K | Angstrom AMU hartree/au hartree/Angstrom.au
FHI-AIMS | Angstrom AMU eV/Angstrom eV/Angstrom^2
Fleur | au (bohr) AMU hartree/au hartree/au^2
CASTEP | Angstrom AMU eV/angstrom eV/angstrom^2
ABACUS | au (bohr) AMU eV/angstrom eV/angstrom.au
LAMMPS | Angstrom AMU eV/Angstrom eV/Angstrom^2
```
For these sets of physical properties, phonon frequency is calculated in THz.
## Default file name, value, and conversion factor
### Default unit cell file name for calculator
Without specifying `-c` option, default file names of unit cell shown below is
searched in current directory. When generating supercells with `-c` option,
the default supercell file names based on those shown below are used.
```
VASP | POSCAR | SPOSCAR
WIEN2k | case.struct | case.structS
QE | unitcell.in | supercell.in
ABINIT | unitcell.in | supercell.in
SIESTA | input.fdf | supercell.fdf
Elk | elk.in | supercell.in
CRYSTAL | crystal.o | -
DFTB+ | geo.gen | geo.genS
TURBOMOLE | control | -
CP2K | unitcell.inp | -
FHI-AIMS | geometry.in | geometry.in.supercell
Fleur | fleur.in | supercell.in
CASTEP | unitcell.cell | supercell.cell
ABACUS | STRU | STRU.in
LAMMPS | unitcell | supercell
```
### Default displacement distances
Without specifying `DISPLACEMENT_DISTANCE` tag or `--amplitude` option, default
displacement distance is used when creating supercells with displacements
`CREATE_DISPLACEMENTS = .TRUE.` or `-d` option. The default value is dependent
on calculator, and the list is shown below:
```
VASP | 0.01 Angstrom
WIEN2k | 0.02 au (bohr)
QE | 0.02 au (bohr)
ABINIT | 0.02 au (bohr)
SIESTA | 0.02 au (bohr)
Elk | 0.02 au (bohr)
CRYSTAL | 0.01 Angstrom
DFTB+ | 0.01 au (bohr)
TURBOMOLE | 0.02 au (bohr)
CP2K | 0.01 Angstrom
FHI-AIMS | 0.01 Angstrom
Fleur | 0.02 au (bohr)
CASTEP | 0.01 Angstrom
ABACUS | 0.02 au (bohr)
LAMMPS | 0.01 Angstrom
```
(frequency_default_value_interfaces)=
### Default unit conversion factor of phonon frequency to THz
```
VASP | 15.633302
WIEN2k | 3.44595837
QE | 108.97077
ABINIT | 21.49068
SIESTA | 21.49068
Elk | 154.10794
CRYSTAL | 15.633302
DFTB+ | 154.10794
TURBOMOLE | 154.10794
CP2K | 112.10516
FHI-AIMS | 15.633302
Fleur | 154.10794
CASTEP | 15.633302
ABACUS | 21.49068
LAMMPS | 15.633302
```
(nac_default_value_interfaces)=
### Default unit conversion factor for non-analytical term correction
```
VASP | 14.399652
WIEN2k | 2000
QE | 2
ABINIT | 51.422090
SIESTA | 51.422090
Elk | 1
CRYSTAL | 14.399652
DFTB+ | 14.399652
TURBOMOLE | 1
CP2K | None (N/A)
FHI-AIMS | 14.399652
Fleur | 1 (but feature N/A)
CASTEP | 14.399652
ABACUS | 51.422090
LAMMPS | 14.399652
```