LPHON POLAR: Difference between revisions
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If the material is polar (i.e. has more than one atom type), a special treatment of the long-range dipole-dipole interaction is required to obtain a smooth phonon dispersion. | If the material is polar (i.e. has more than one 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 {{TAG|LPHON_POLAR}}=.TRUE. and supplying the static dielectric tensor ({{TAG|PHON_DIELECTRIC}}) and the Born-effective charges ({{TAG|PHON_BORN_CHARGES}}) which can be obtained | This is activated by setting {{TAG|LPHON_POLAR}}=.TRUE. and supplying the static dielectric tensor ({{TAG|PHON_DIELECTRIC}}) and the Born-effective charges ({{TAG|PHON_BORN_CHARGES}}) which can be obtained in a separate VASP calculation using the {{TAG|LEPSILON}} or {{TAG|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 ({{TAG|PHON_G_CUTOFF}}). | ||
{{NB|mind| Only available as of VASP 6.3.2.}} | {{NB|mind| Only available as of VASP 6.3.2.}} | ||
Revision as of 09:28, 20 July 2022
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 and PHON_BORN_CHARGES must also be set.
If the material is polar (i.e. has more than one 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 in a separate VASP calculation 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
QPOINTS, LPHON_DISPERSION, PHON_NWRITE, PHON_DIELECTRIC, PHON_BORN_CHARGES, PHON_G_CUTOFF