Here are some tips I get from my past experience with VASP. I don’t know where to put them so they are here.

  1. Use LREAL = Auto for large supercells simulations, I was once warned by VASP:

    You have a (more or less) ‘large supercell’ and for larger cells it might be more efficient to use real-space projection operators. Therefore, try LREAL= Auto in the INCAR file. Mind: For very accurate calculation, you might also keep the reciprocal projection scheme (i.e. LREAL=.FALSE.).

  2. POTCAR is matched to POSCAR by ordering, not by atom name. So be careful with the ordering of atoms.

  3. Disabling WAVECAR, CHGCAR, and CHG output to save disk space by setting the following variables: