TMPCAR is a binary file which will only be generated for dynamic simulations and relaxation jobs using full wavefunction predication. It contains the ionic positions and wavefunction of the previous two steps which are needed for the extrapolation of the wavefunctions. It is possible to use the file TMPCAR for continuation jobs setting the flag ISTART=3 on the file INCAR (see description of INCAR, section 7.10, 7.23).