LRPA: Difference between revisions

Revision as of 09:21, 13 June 2024

LRPA = .TRUE. | .FALSE.
Default: LRPA = .FALSE.

Description: LRPA=.TRUE. includes local field effect on the Hartree level only.

For LRPA=.TRUE. local field effects are included on the Hartree level only. This means that cell periodic microscopic changes of the local potential related to the change of the Hartree potential are included.

For LRPA=.FALSE. changes of the Hartree and the exchange correlation potential are included. This usually increases the dielectric constants. The final values for the dielectric tensor can be found in the OUTCAR file after the lines.

MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in RPA (Hartree))

For LRPA=.FALSE. the dielectric tensor is written after the lines:

MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in DFT)

The dielectric tensor excluding local field effects is always calculated (regardless of LRPA). The piezoelectric tensors and the Born effective charges as well as the ionic contributions the to dielectric tensor are only calculated for LRPA=.FALSE..

Warning: We only recommend using the LRPA flag in combination with LEPSILON or LCALCEPS, where the treatment of the terms beyond RPA is unambiguous. In the many-body perturbation theory calculations various approximations beyond RPA can used, hence more precise control of the included terms should be used via tags LHARTREE, LADDER, and LFXC.

@@ Line 10: / Line 10: @@
   MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in DFT)
 The dielectric tensor ''excluding'' local field effects is always calculated (regardless of {{TAG|LRPA}}). The piezoelectric tensors and the Born effective charges as well as the ionic contributions the to dielectric tensor are only calculated for {{TAG|LRPA}}=.FALSE..
+{{NB|warning|We only recommend using the {{TAG|LRPA}} flag in combination with {{TAG|LEPSILON}} or {{TAG|LCALCEPS}}, where the treatment of the terms beyond RPA is unambiguous. In the many-body perturbation theory calculations various approximations beyond RPA can used, hence more precise control of the included terms should be used via tags {{TAG|LHARTREE}}, {{TAG|LADDER}}, and {{TAG|LFXC}}.}}
-We only recommend using the {{TAG|LRPA}} flag in combination with {{TAG|LEPSILON}} or {{TAG|LCALCEPS}}, where the treatment of the terms beyond RPA is unambiguous. In the many-body perturbation theory calculations various approximations beyond RPA can used, hence more precise control of the included terms should be used via tags {{TAG|LHARTREE}}, {{TAG|LADDER}}, and {{TAG|LFXC}}.
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