Location of available forcefields

[CurtisColwell]

This feels like a silly question, but is there a list of available forcefields? When defining the forcefield, they all seem like they are in an amber/ folder, but I cannot find this folder.

[mikemhenry]

Good question! Currently openfe uses https://github.com/openmm/openmmforcefields to parametrize systems, so that repository is where most of the force field files are located. The exception to that are force fields from https://openforcefield.org/ which are located here: https://github.com/openforcefield/openff-forcefields (they are located in a separate repo since openff provides nice python tooling to use their force fields, where charm and amber (and others) do not).

[CurtisColwell]

Thanks, but I still can't find the amber/ folder that is being referred to by

forcefields=[
'amber/ff14SB.xml',
'amber/tip3p_standard.xml',
'amber/tip3p_HFE_multivalent.xml',
'amber/phosaa10.xml'
],

I'm having trouble modifying this without getting ValueError: Could not locate file "amber/ff19SB.xml"

[mikemhenry]

Can you check what version of openmmforcefields you are using with mamba list openmmforcefields (replace mamba with conda or micromamba if needed). Those files are here: https://github.com/openmm/openmmforcefields/tree/main/openmmforcefields/ffxml/amber but it sounds like you are getting an error, I thought you were just looking for the files.

If you can post the code that is generating this error, as well as the version of openfe you are using, I can help figure out what is going on.

[CurtisColwell]

That's it! It looks like the main branch does have protein.ff19SB.xml, but the releases do not. Thanks!!

[mikemhenry]

I am in the middle of cutting a new release, so with any luck you will wake up tomorrow with some fresh force fields!

[IAlibay]

amber/ff19SB.xml

Just as an FYI - OpenFE doesn't support ff19SB right now for alchemical systems, the behaviour is likely undefined.