Thank you for the tip -- I've had some success in using xtb directly, and now I'd like to use it from within OpenMM. The only example code I've found was the TestXtbForce class in the test suite for openmm-xtb, but I wasn't sure how to use the low-level XtbForce with higher-level OpenMM classes/meth...

Great, thanks for the information. I've found that discoverability of force fields is a bit rough -- if anyone has a specific suggestion of a FF I can use out-of-the-box with OpenMM (or convert from another system and drop in), I'd appreciate it. At this point, perfect accuracy isn't as important as...

I'm doing some graphene simulations in water, and am having some setup problems. In this instance I'm starting from a SMILES string and using RDKit to add appropriate hydrogens, then converting to a PDB file. As a result, the PDB residue field is unknown and set to UNL. I tried using the SMIRNOFFTem...