Quantum chemistry program executor and IO standardizer

 QCEngine provides a wrapper to ingest and produce QCSchema for a variety of
 quantum chemistry programs, most notably Psi4, NWchem, RDKit and Mopac.
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 Other supported (possibly proprietary) packages include DFTD3, MOLPRO, MPD2,
 OpenMM, Q-Chem, Turbomole, xtb, CFour, GAMESS, Terachem and TorchANI.