openforcefield/openff-forcefields

Non-integer charges

aniketsh opened this issue · 2 comments

aniketsh commented

Hi,

I am getting some non-integer charges with am1bcc, for instance 0.003. Is there any fix for this already implemented?

OS: MacOS
OFF version: 1.3

j-wags commented

Hi @aniketsh,

Thanks for the report. We've seen this problem before, but we don't have a solution implemented. I had suggested a few options in openforcefield/openff-toolkit#456 but didn't get much feedback at the time.

If this is indeed what you're asking about, would you be willing to close this issue and move this discussion over there?

This shouldn't be too hard once we settle on a desired API for the rounding. Basically, we probably want option 1 on that issue (apply equal offsets to all atoms by default to ensure that the partial charges sum to the total formal charge, but let the user provide a manual override if they DON'T want rounding to be applied).

aniketsh commented

@j-wags
Sure, will do that.