LPHON POLAR

LPHON_POLAR = .TRUE. | .FALSE.

Default: LPHON_POLAR

= .FALSE.

Description: LPHON_POLAR includes dipole-dipole corrections in the computation of the phonon dispersion. For this mode PHON_DIELECTRIC, PHON_BORN_CHARGES must also be set.

If the material is polar (i.e. has more than one different atom type) 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 on a separate VASP run using the LEPSILON or LCALCEPS tag. The long-range part is evaluated using an Ewald sum with the number of G-vectors in reciprocal space being determined using a cutoff length (PHON_G_CUTOFF).

Mind: Only available as of VASP 6.3.2.

Related tags and articles