The WAVECAR file is a binary file containing following data:
NBAND number of bands ENCUTI 'initial' cut-off energy AX 'initial' basis vectors defining the supercell CELEN ('initial') eigenvalues FERWE ('initial') Fermi-weights CPTWFP ('initial') wavefunctionsUsually WAVECAR provides excellent starting wavefunctions for a continuation job. For dynamic simulation (IBRION=0) the wavefunctions may be predicted for the next step: i.e. the file is compatible with CONTCAR. The WAVECAR, CHGCAR and the CONTCAR file can be used consistently for a molecular dynamics continuation job. For static calculations and relaxations (IBRION=-1,1,2) the written wavefunctions are the solution of KS-equations for the last step. From VASP version 2.0 it is possible to avoid, that the WAVECAR is written out by setting
LWAVE & = & .FALSE.in the INCAR file (see section 7.43)
Mind: For dynamic simulations (IBRION=0) the WAVECAR file contains some predicted wavefunctions compatible with CONTCAR. If you use the wavefunctions externally copy CONTCAR to POSCAR and make another static (ISTART=1; NSW=0) continuation run with ICHARG=1. For reasons of safety do the same for relaxation runs (IBRION=1,2).