I see from the phonopy web page 1 that the physical unit systems used for the calculators are different for different codes 1. On the same page, it is mentioned that "For these sets of physical properties, phonon frequency is calculated in THz." Does it mean that the final unit for frequency and group velocity in
gruneisen.yaml for VASP and QE codes are the same?
I was told by Prof. Togo, the developer of phonopy, that the unit of frequency is considered the same in VASP and QE, but that of group velocity is not.
Could someone please help me: how can I convert the unit of velocity in the QE
band.yaml file to the units of the VASP
band.yaml format (THz/Angstrom).
The unit in the VASP
band.yaml file is THz/Angstrom while in the
band.yaml file of QE it may be in THz/Bohr (not sure). To make the QE format of
VASP band.ymal, can we do the conversion like below?
1bohr = 0.529177249 Angstrom 1/bohr = 1/0.529177249 = 1.88972598857
So I need to multiply the velocity in
band.yaml of QE by 1.88972598857?
My half-finished conversation on the phonopy mailing list can be found here 2
An example of the VASP
band.yaml and QE
band.yaml can be found here 3.