GitLab

* Add benchmarks from Amber20 benchmark suite to standard benchmark script

* Add ensemble option; don't change hydrogen mass in amber input files

* Download and extract .tar.gz using pure python code, no wget/tar dependencies

* Rename amber tests

* add opc and opc3 models

* update to match https://bioinformatics.cs.vt.edu/~izadi/OPC_Gromacs/opc.top



* opc box, converted from ambertools-22.0-py38h6177452_1/dat/leap/lib/opcbox.off

* change values to make serialized system match one created from prmtop as close as possible

* unit test for opc water

* opc - final values, match frcmod.opc; derivation in comments

* opc3 water - final values, shows derivation

* opc3box made from ambertools 22 dat/leap/lib/opc3box.off

* add opc3 water test

* add opc and opc3 to docs

* move tests to TestForceField.py

* move opc tests out of amoeba tests, oops

* move opcbox and opc3box pdb files
Co-authored-by: Alex Izvorski <alex@genesistherapeutics.ai>