Alex Izvorski

@zhang-ivy Do you think the split as described is a good idea? Any tips how it can be done reusing code from openmmforcefields convert_amber.py? I have some other more detail-oriented...

@peastman "I don't think we'd want to bundle all of them with OpenMM itself" - Why not? If we follow the same pattern as now, to get working ions for...

@jchodera I just added a PR for this. I would request we put the ion files in openmm rather than openmmforcefields, since without it some of the water models here...

@rkingsbury The conversion is done in PR #3773, please give it a try! If you can make a water and salt box and compare its Amber energy vs the energy...

@peastman Thanks for explaining that. So, no changes to a force object propagate to existing contexts at all? Both parameters (things that have "parameter" in the name, like `setParticleParameters()`), and...

@peastman Also - how to make this kind of issue more obvious - if this doesn't work correctly, it probably should throw an exception, but when exactly should that happen...

@peastman Thanks for the faq update. "Once you create a Context, the System it was created for is treated as immutable. Any further changes to the System are ignored. That...

@peastman Okay makes sense. I hope if the behavior is not as expected tracking down the root cause would be useful. Why only "incorrect behavior on the reference platform" though?...

@peastman "Remember that you're allowed to create multiple Contexts for the same System, and also to modify the System in between" - What is the use typical case for this?...

By the way, this seems to succeed and outputs a reasonable xml file: `python openmm/devtools/forcefield-scripts/processAmberForceField.py ambertools-20.9/dat/leap/parm/frcmod.ff19SB` However the frcmode file has a bunch of CMAP sections, and it seems they...