Alex Izvorski

@peastman Could you describe what form you'd like this PR to have? I'm a bit unsure of the details. Do you want to just have one opc.xml file which is...

@peastman Okay, I changed #3819 to have merged files as you described, could you have a look?

Hi guys - I'm very happy to hear this is moving forward! I'm interested in being able to use especially rotational and helical symmetry - both would be (typically) periodic...

@peastman Ah, that was quoting from what you mentioned in this thread: https://github.com/openmm/openmm/issues/1437#issuecomment-202616443 u, v, w are (scalar) coefficients and a, b, c the unit cell vectors

@peastman Hmm, as you said, the fixed vector method is good for symmetric assemblies with a fixed number of units (eg a dimer); the cell-size-dependent method is good for assemblies...

@CoryKornowicz Thanks for bringing up OPC3-pol, I hadn't seen it before. From a quick look at the paper, it looks like a 4-site model with a Drude particle. Yes, it...

@CoryKornowicz Regarding ion models for OPC3-pol: it seems like Pengfei Li and Kenneth Merz's group fit ion parameters to models a little after they come out. For example have a...

> Thanks so much for contributing this! We're currently on AmberTools 20.15---would it make sense to include this in a full update of all Amber force fields to AmberTools 22?...

@jchodera I saw your https://github.com/openmm/openmmforcefields/pull/184 - did AmberTools 21 work okay with the existing conversion setup?

> Any idea what has changed between 20 and 22? @peastman I don't know exactly what the release notes say, but from a quick diff looks like the main additions...