VASP Input files: POTCAR

The POTCAR file contains the pseudopotentials (for more than one element, simply concatenate POTCAR files using the UNIX command cat, if compressed, use zcat). The POTCAR file also contains information about the atoms (i.e. their mass, their valence, the energy of the atomic reference configuration for which the pseudopotential was created etc.).

For a case where you want to generate a system of XY elements, remember since your POTCAR file contains X first and then Y, you should be consistent while putting the positions in POSACR file, i.e., write the positions for X first and then Y. For X and Y elements in your simulation you should do like the following:

> gunzip /usr/local/vasp/potpaw_GGA/X/POTCAR.Z > POTCAR_X
> gunzip /usr/local/vasp/potpaw_GGA/Y/POTCAR.Z > POTCAR_Y
> cat POTCAR_X POTCAR_Y > POTCAR'

Potentials are available in the following directory:

/usr/local/vasp

NOTE: the contents of this folder is accessible only to the members of the VASP group.

Depending on what kind of potential you are looking for, you have to go further to chose your directory, such as if you want to use GGA potential you should grab /usr/local/vasp/potpaw_GGA/Al/POTCAR.Z

Also, there are typically soft and hard potential for each element. Depending on your application you should choose them.