The WAVECAR file is a binary file containing the 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') wavefunctions
Usually WAVECAR provides excellent starting wavefunctions for a continuation job. For dynamic simulation (IBRION=0) the wavefunctions in the file are usually those 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 the KS-equations for the last step. It is possible to avoid, that the WAVECAR is written out by setting
LWAVE = .FALSE.
in the INCAR file.
Mind: For dynamic simulations (IBRION=0) the WAVECAR file contains predicted wavefunctions compatible with CONTCAR. If you want to use the wavefunctions for additional calculations, first copy CONTCAR to POSCAR and make another static (ISTART=1; NSW=0) continuation run with ICHARG=1.