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 (see section 6.49)
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.