Sub-Space-Matrix is not hermitian
Most common reasons:
- unreasonable input geometry (e.g. after a relaxation step)
- Solution: fix geometry
- Error encountered when initializing a parallelized ISIF=3 relaxation
- Solution: Replacing e.g. NPAR=4 with NCORE=16 has in some cases solved the problem
- problems during reading of the CHGCAR file (e.g. complaint that the dimensions have changed after a change in k-point grid)
- Solution: remove CHGCAR file and start density from scratch
- problems during initialization altogether
- Solution: try completing the run and restarting with from the CHGCAR and WAVECAR; if that does not work: try the same with IALGO=48 (may give related warnings before restarting)
- From the VASP forum: If the error persist although you switched to the Davidson algorithm:
- on some architectures (especially SGI) some LAPACK routines are not working
- properly. However, it is possible to avoid the usage of the ZHEGV subroutine by commenting the line #define USE_ZHEEVX in davidson.F, subrot.F, and
- wavpre_noio.F and recompiling VASP.
- --->If VASP is not well-compiled for the architecture being used, reducing NCORE might solve the problem altogether.
if nothing else works: try changing PREC Normal to Accurate