LRPA: Difference between revisions
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Description: {{TAG|LRPA}}=.TRUE. includes local field effect on the Hartree level only. | Description: {{TAG|LRPA}}=.TRUE. includes local field effect on the Hartree level only. | ||
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For {{TAG|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 {{TAG|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 {{TAG|LRPA}}=.FALSE. changes of the Hartree ''and the exchange correlation potential'' are included | ::<math>\epsilon_{\mathbf{G}, \mathbf{G}^{\prime}}^{\mathrm{RPA}}(\mathbf{q}, \omega)=\delta_{\mathbf{G}, \mathbf{G}^{\prime}}-\frac{4 \pi}{|\mathbf{G}+\mathbf{q}|\left|\mathbf{G}^{\prime}+\mathbf{q}\right|} \chi_{\mathbf{G}, \mathbf{G}^{\prime}}^0(\mathbf{q}, \omega)</math> | ||
For {{TAG|LRPA}}=.FALSE. changes of the Hartree ''and the exchange correlation potential'' are included | |||
::<math>\epsilon_{\mathbf{G}, \mathbf{G}^{\prime}}^{\mathrm{DFT}}(\mathbf{q}, \omega)=\delta_{\mathbf{G}, \mathbf{G}^{\prime}}-\frac{4 \pi}{|\mathbf{G}+\mathbf{q}|\left|\mathbf{G}^{\prime}+\mathbf{q}\right|} \chi_{\mathbf{G}, \mathbf{G}^{\prime}}^0(\mathbf{q}, \omega)\left[\delta_{\mathbf{G}, \mathbf{G}^{\prime}}-f_{\mathbf{G}, \mathbf{G}^{\prime}}^{\mathbf{xc}}(\mathbf{q}, \omega) \chi_{\mathbf{G}, \mathbf{G}^{\prime}}^0(\mathbf{q}, \omega)\right]^{-1} </math> | |||
This usually increases the dielectric constants. The final values for the dielectric tensor can be found in the {{TAG|OUTCAR}} file after the lines. | |||
MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in RPA (Hartree)) | MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in RPA (Hartree)) | ||
For {{TAG|LRPA}}=.FALSE. the dielectric tensor is written after the lines: | For {{TAG|LRPA}}=.FALSE. the dielectric tensor is written after the lines: | ||
Revision as of 09:30, 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. |
Related tags and articles
LEPSILON, LCALCEPS, LHARTREE, LADDER, LFXC