qupkake -mp 1 but xtb still using many threads

[UnixJunkie]

Apparently, the maximum number of cores option given to qupkake is not passed down to xtb.
Maybe, qupkake should set the env. vars OMP_NUM_THREADS and MKL_NUM_THREADS to the given value prior to running xtb.

[UnixJunkie]

the -P option passed to xtb should percolate from the -mp option passed to qupkake
Cc @ghutchis

[ghutchis]

Yeah, I agree, but it'll take me a bit to get to that - getting the next Avogadro and Open Babel releases, plus the start of classes this week.