LMONO: Difference between revisions

Revision as of 12:57, 14 December 2017

LMONO = .TRUE. | .FALSE.
Default: LMONO = .FALSE.

Description: LMONO switches on monopole-monopole corrections for the total energy.

The flag switches on monopole corrections for charged systems. The correction is calculated only a posteriori for the total energy. No correction to the potential is calculated. If corrections for the potential are desired as well, please use LDIPOL instead (for LDIPOL=.TRUE., VASP automatically determines whether the system is charged and activates the monopole corrections automatically).

The primary use of this flag is for defect calculations in charged supercells, as well as charged 0D systems (molecules and atoms). VASP also automatically calculates corrections to the total energy related to repeated dipoles (IDIPOL=4). The user then needs to decide whether those are sensible or not. Specifically, for super cells using periodic boundary conditions, it is often not possible to determine the dipole at the defect site accurately, whereas for 0D systems (i.e. atoms and molecules) the dipole can be determined accurately.

Related Tags and Sections

Monopole Dipole and Quadrupole corrections, NELECT, EPSILON, IDIPOL, DIPOL, LDIPOL, EFIELD

Examples that use this tag

References

Cite error: <ref> tag with name "Neugebauer92" defined in <references> has group attribute "" which does not appear in prior text.

Contents

@@ Line 1: / Line 1: @@
 {{TAGDEF|LMONO|.TRUE. {{!}} .FALSE.|.FALSE.}}
-Description: {{TAG|LMONO}} switches on monopole-monopole interaction correction to the potential.
+Description: {{TAG|LMONO}} switches on monopole-monopole corrections for the total energy.
 ----
-Due to the periodic boundary conditions, not only the total energy converges slowly with respect to the size of the supercell, but also the potential and the forces are affected by finite size errors. This effect can be counterbalanced by setting {{TAG|LDIPOL}}=.TRUE. (dipole corrections) and/or {{TAG|LMONO}}=.TRUE. (monopole corrections) in the {{FILE|INCAR}} file. For {{TAG|LDIPOL}}=.TRUE.,a linear and for {{TAG|LMONO}}=.TRUE., a quadratic electrostatic potential is added to the local potential, correcting the errors introduced by the periodic boundary conditions. This is in the spirit of Neugebauer ''et al.''<ref name="Neugebauer92"/> (but more general and the total energy has been correctly implemented right away). The biggest advantage of this mode is that leading errors in the forces are corrected, and that the work-function can be evaluated for asymmetric slabs. The disadvantage is that the convergence to the electronic groundstate might slow down considerably (''i.e.'', more electronic iterations might be required to obtain the required precision). It is recommended to use this mode only after pre-converging the orbitals without the {{TAG|LDIPOL}} flag, and the center of charge should be set in the {{FILE|INCAR}} file ({{TAG|DIPOL}}= center of mass). The user must also ensure that the cell is sufficiently large to determine the dipole moment with sufficient accuracy. If the cell is too small, charge might swap through the vacuum, causing very slow convergence (often convergence improves with the size of the supercell).
+The flag switches on monopole corrections for charged systems. The correction is calculated only a posteriori for the total energy. No correction to the potential is calculated.  If corrections for the potential are desired as well, please use {{TAG|LDIPOL}} instead (for {{TAG|LDIPOL}}=.TRUE., VASP automatically determines whether the system is charged and activates the monopole corrections automatically).
+The primary use of this flag is for defect calculations in charged supercells, as well
+as charged 0D systems (molecules and atoms). VASP also automatically calculates
+corrections to the total energy related to repeated dipoles ({{TAG|IDIPOL}}=4).
+The user then needs to decide whether
+those are sensible or not. Specifically, for super cells using periodic boundary conditions,
+it is often not possible to determine the dipole at the defect site accurately,
+whereas for 0D systems (i.e. atoms and molecules) the dipole can be determined
+accurately.
 == Related Tags and Sections ==