https://vasp.at/forum/viewtopic.php?t=214
WARNING in EDDRMM: call to ZHEGV failed, returncode = 6 3 9 - VASP Forum
https://www.unix.com/man_page/debian/3/zhegv/
zhegv(3) debian man page | unix.com
Man page for zhegv(3) on debian, from the unix.com online archive.
man pagedebianunix