PHON_DIELECTRIC
PHON_DIELECTRIC = [3x3 real]
| Default: PHON_DIELECTRIC | = None |
Description: PHON_DIELECTRIC sets the static dielectric tensor to be used for the dipole-dipole corrections in the computation of the phonon dispersion. This is only used when LPHON_POLAR=.TRUE.
If the material is non-metallic and polar (i.e. two or more atoms in the unit cell carry nonzero Born effective charge tensors), a special treatment of the long-range dipole-dipole interaction is required to obtain a smooth phonon dispersion. This is activated by setting LPHON_POLAR=.TRUE. and supplying the static dielectric tensor (PHON_DIELECTRIC) and the Born-effective charges (PHON_BORN_CHARGES) which can be obtained in a separate VASP calculation using the LEPSILON or LCALCEPS tag. The dipole-dipole part of the interatomic force-constants is evaluated using an Ewald summation with the number of vectors determined by the cutoff length (PHON_G_CUTOFF).
| Mind: Only available as of VASP 6.3.2. |
Related tags and articles
QPOINTS, LPHON_DISPERSION, PHON_NWRITE, LPHON_POLAR, PHON_BORN_CHARGES, PHON_G_CUTOFF