LOCPOT: Difference between revisions

Revision as of 15:46, 20 January 2021

The LOCPOT file stores the local potential (in eV).

To write this file, the line

LVTOT = .TRUE.

must be set in the INCAR file. Depending on LVHAR the total local Kohn-Sham potential (LVHAR=.FALSE.) or the sum of the Hartree and ionic potential ([[{{{1}}}]]) is written to the LOCPOT file.

Note that {{TAG|LVHAR} was added at some point in vasp.5, please check whether your version supports this tag.

Mind: Versions not supporting {{TAG|LVHAR}=.FALSE. might write out either the total Kohn-Sham potential or the electrostatic potential. Please check main.F searching for LEXCHG=-1 in main.F. If the line LEXCHG=-1 is commented out, the exchange correlation is added.

The LOCPOT file format is similar to that of the CHGCAR file but it does not have the same data arrangement. For spin unpolarized calculations it contains a single dataset with the potential. For collinear spin calculations (ISPIN=2), it contains two datasets: spin up and spin down. For noncollinear calculations (LNONCOLLINEAR=.TRUE.), it contains four datasets with spinor representation of the potential.

For VASP.5.2.12 and newer: LVTOT=.TRUE. writes the local potential including the exchange-correlation contribution on LOCPOT. LVHAR=.TRUE. writes the local potential excluding the exchange-correlation potential on LOCPOT.

@@ Line 1: / Line 1: @@
-The {{TAG|LOCPOT}} file contains the total local potential (in eV).
+The {{TAG|LOCPOT}} file stores  the local potential (in eV).
 To write this file, the line
@@ Line 5: / Line 5: @@
   LVTOT = .TRUE.
-must exist in the {{TAG|INCAR}} file. In the present version, the only electrostatic part of the potential is written (exchange correlation is not added). This is desirable for the evaluation of the work-function, because the electrostatic potential converges more rapidly to the vacuum level than the total potential. However if the exchange correlation potential is to be included, change one line in main.F:
+must be set in the {{TAG|INCAR}} file. Depending on {{TAG|LVHAR}} the total local
- ! comment out the following line to add  exchange correlation
+Kohn-Sham potential ({{TAG|LVHAR}}=.FALSE.) or the sum of the Hartree and ionic potential ({{TAG|LVHAR}=.FALSE.}}) is written to the LOCPOT file.
- !         INFO%LEXCHG=-1
-          CALL POTLOK(...)
+Note that {{TAG|LVHAR} was added at some point in vasp.5, please check whether your version
+supports this tag.
 Mind:
-Older versions might have had a different behavior, when they were retrieved from the server. Please always check yourself, whether main.F is working in the way you expect (simply search for ''LEXCHG=-1'' in main.F). If the line ''LEXCHG=-1'' is commented out, the exchange correlation is added. It is recommended to avoid wrap around errors, when evaluating {{TAG|LOCPOT}}. This can be done by specifying {{TAG|PREC}}=''High'' in the {{TAG|INCAR}} file.
+Versions not supporting {{TAG|LVHAR}=.FALSE. might write out either the total Kohn-Sham potential or the electrostatic potential. Please check  main.F searching for ''LEXCHG=-1'' in main.F. If the line ''LEXCHG=-1'' is commented out, the exchange correlation is added.
 The {{TAG|LOCPOT}} file format is similar to that of the {{TAG|CHGCAR}} file but it does not have the same data arrangement.