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 Choice of force calculator. LAMMPS interface is provided as an external tool by Abel Carreras.

List of force calculators#

Short tutorials for the force calculators are found in the following pages.

The VASP DFPT interface reads vasprun.xml and creates FORCE_CONSTANTS file.

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          | sSTRU
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

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

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