Electrostatic corrections: Difference between revisions

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| Does the system have a net dipole moment?
| Does the system have a net dipole moment?
| Relevant INCAR tags for monopole/dipole corrections
| Relevant INCAR tags for monopole/dipole corrections
| Do energies converge with cell dimension?
|-
|-
| 3D
| 3D
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| No
| No
| None
| None
|-
| 3D
| Yes
| No
|{{TAG|NELECT}}, {{TAG|LMONO}}, {{TAG|EPSILON}}
|-
| 3D
| No
| Yes
| Yes
| {{TAG|DIPOL}}, {{TAG|IDIPOL}}, {{TAG|EPSILON}}
|-
|-
| 3D
| 3D
| Yes
| Yes
| |{{TAG|NELECT}}, {{TAG|DIPOL}}, {{TAG|IDIPOL}}, {{TAG|EPSILON}}
|-
| 2D
| No
| No
| None
|-
| 2D
| Yes
| Yes
| No
| No
|{{TAG|NELECT}}: to set the charge
| {{TAG|NELECT}}
{{TAG|LMONO}}: monopole corrections, only implemented for cubic cells
 
{{TAG|EPSILON}}: scales monopole correction by dielectric constant of the medium
| If the correct {{TAG|EPSILON}} value is used, the energies and relative energies will not depend on cell size. For solids, see {{TAG|LCALCEPS}} and {{TAG|LEPSILON}}
|-
|-
| 2D
| 2D
| No
| No
| Yes
| Yes
| {{TAG|IDIPOL}}=1,2,3: direction in which to apply the dipole correction to the total energy
| {{TAG|IDIPOL}}, {{TAG|LDIPOL}}, {{TAG|DIPOL}}
{{TAG|LDIPOL}}: enable dipole correction to the potential and forces
 
{{TAG|DIPOL}}: center of mass to compute the dipole moment
| Energies do not depend on the vacuum used (if sufficient vacuum is available)
|-
|-
| 2D
| 2D
| Yes
| Yes
| Yes
| {{TAG|NELECT}}
|-
| 1D
| No
| No
| No
| {{TAG|NELECT}}: to set the charge
| None
| Absolute energies do not converge with cell dimension, but energy differences might be useful
|-
|-
| 2D
| 1D
| Yes
| Yes
| No
| {{TAG|NELECT}}
|-
| 1D
| No
| Yes
| Yes
| {{TAG|NELECT}}: to set the charge
| Not implemented
| Absolute energies do not converge with cell dimension, but energy differences might be useful
|-
|-
| 0D (isolated molecules)
| 1D
| Yes
| Yes
| Yes
| Yes
| {{TAG|NELECT}}: to set the charge
| Not implemented
{{TAG|LMONO}}: monopole corrections, only implemented for cubic cells and only corrects the energy
 
{{TAG|LDIPOL}}: monopole corrections with corrections for the potentials
| Energies do not depend on cell dimension (for large enough cells)
|-
|-
| 0D (isolated molecules)
| 0D
| No
| No
| None
|-
| 0D
| Yes
| Yes
| No
| No
| {{TAG|NELECT}}: to set the charge
| {{TAG|NELECT}}, {{TAG|LMONO}}, {{TAG|LDIPOL}}
{{TAG|LMONO}}: monopole corrections, only implemented for cubic cells and only corrects the energy
 
{{TAG|LDIPOL}}: monopole corrections with corrections for the potentials
| Energies do not depend on cell dimension (for large enough cells)
|-
|-
| 0D (isolated molecules)
| 0D
| No
| No
| Yes
| Yes
| {{TAG|LDIPOL}}: dipole corrections with corrections for the potentials included
| {{TAG|LDIPOL}}
| Energies do not depend on cell dimension (for large enough cells)
|-
| 0D
| Yes
| Yes
| {{TAG|NELECT}}, {{TAG|LMONO}}, {{TAG|LDIPOL}}
|}
|}


Revision as of 09:15, 19 October 2023

For charged cells or for calculations of molecules and surfaces with a large dipole moment, the energy converges very slowly with respect to the size of the supercell. Using methods discussed by Makov et al.[1] and Neugebauer et al.[2], VASP can correct for the leading errors (in many details, we have taken a more general approach, though).

Summary of relevant INCAR tags

This section contains a summary of all the INCAR tags that are currently implemented for performing monopole, dipole and quadrupole corrections using VASP. Please see the relevant pages of the respective tags for more detailed information.

Dimensionality of the system Does the system have net charge? Does the system have a net dipole moment? Relevant INCAR tags for monopole/dipole corrections
3D No No None
3D Yes No NELECT, LMONO, EPSILON
3D No Yes DIPOL, IDIPOL, EPSILON
3D Yes Yes NELECT, DIPOL, IDIPOL, EPSILON
2D No No None
2D Yes No NELECT
2D No Yes IDIPOL, LDIPOL, DIPOL
2D Yes Yes NELECT
1D No No None
1D Yes No NELECT
1D No Yes Not implemented
1D Yes Yes Not implemented
0D No No None
0D Yes No NELECT, LMONO, LDIPOL
0D No Yes LDIPOL
0D Yes Yes NELECT, LMONO, LDIPOL


Tip: If an external electrostatic field is desired for slab, or molecular calculations, see EFIELD

Current limitations

For the current implementation, there are several restrictions; please read carefully:

  • Charged systems:
Quadrupole corrections are only correct for cubic supercells (this means that the calculated 1/L3 corrections are wrong for charged supercells if the supercell is non-cubic). In addition, we have found empirically that for charged systems with excess electrons (NELECT>NELECTneutral) more reliable results can be obtained if the energy after correction of the linear error (1/L) is plotted against 1/L3 to extrapolate results manually for L→∞. This is due to the uncertainties in extracting the quadrupole moment of systems with excess electrons.
  • Potential corrections are only possible for orthorhombic cells (at least the direction in which the potential is corrected must be orthogonal to the other two directions).

Related Tags and Sections

NELECT, EPSILON, DIPOL, IDIPOL, LDIPOL, LMONO, EFIELD

Examples that use this tag

References

  1. ↑ G. Makov and M. C. Payne, Phys. Rev. B 51, 4014 (1995).
  2. ↑ J. Neugebauer and M. Scheffler, Phys. Rev. B 46, 16067 (1992).

Contents

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