Interfaces to calculators

The interfaces for VASP, WIEN2k, Quantum ESPRESSO (QE), ABINIT, Elk, SIESTA, CRYSTAL, and TURBOMOLE 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.

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/
SIESTA    | au (bohr)  AMU           eV/Angstrom   eV/
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

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 name for unit cell is used as shown below:

WIEN2k    | case.struct
QE        |
SIESTA    | input.fdf
Elk       |
CRYSTAL   | crystal.o
DFTB+     | geo.gen
TURBOMOLE | control

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)

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

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

Tutorials for calculators

VASP DFPT force constants

Using VASP DFPT feature, force constants are directly calculated. Phonopy VASP DFPT interface reads vasprun.xml and creates FORCE_CONSTANTS file.

For FHI-aims

For FHI-aims, there is a special command, phonopy-FHI-aims. This tool is maintained by FHI-aims community and questions may be sent to the FHI-aims mailing list.