WAVECAR

Quick Description: This huge file is great to use as a bridge between one job and another, because "...the WAVECAR file which stores the final wave functions. To speed up calculations, VASP usually tries to read this file upon startup. At the end of calculations, the file is written (or if it exists overwritten)." - Penn State's Materials Simulations Tutorial

Prerequisites: See "Submitting Jobs".

Notes: To write the WAVECAR, the following INCAR settings are necessary...

ISTART = 0
LWAVE=.TRUE.
LPARD=.FALSE.
LCHARG=.FALSE.

 Then you can go on to use this to produce your CHGCAR, PARCHG, carry on an optimization without regenerating this file.... etc...