LOCPOT
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 (LVHAR=.FALSE.) is written to the LOCPOT file.
Note that LVHAR was added at some point in vasp.5, please check whether your version supports this tag (the tag is written out at the beginning of the OUTCAR file).
Mind: Versions not supporting LVHAR might write either the total Kohn-Sham potential or the electrostatic potential. Please check main.F by searching for LEXCHG=-1 in main.F. If the line LEXCHG=-1 is commented out, the exchange-correlation potential is added, whereas if the line is present, only the electrostatic potential is written to the file.
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.