OFF-EP-0009

[mattwthompson]

• [x] Add LJPME as an option (#11)
• [x] Explicitly do not resolve #15 #50
• [x] Explicitly do not resolve #16
• [x] Do another typo pass-through
• [ ] Find link for Amber LJPME
• [ ] Find link for CHARMM LJPME
• [x] Incorporate relevant Shirts comments:
  • [ ] https://github.com/openforcefield/standards/pull/44#discussion_r1221734440 - not going to be explicit about this, but worrying about LAMMPS's implementation is not in scope here
  • [ ] https://github.com/openforcefield/standards/pull/44#discussion_r1221736601 valid but not directly relevant
  • [ ] https://github.com/openforcefield/standards/pull/44#discussion_r1221739961 not in scope here
• [x] Chodera comments from 9/5/23 SMIRNOFF committee meeting:
  • [x] Possible incompatibilities with Lorentz-Berthelot mixing rules?
  • [x] Does it make sense to use "conducting boundary" language?
  • [x] Are both the 12 and 6 terms included in reciprocal space?
  • [x] What about non-12-6 potentials?

[mattwthompson]

Jotting down some notes:

After reading the docs and trying to grok the implementation in some OpenMM source code, I'm moving to just use "Ewald3D". I'm not confident that a conducting boundary is not used, but as I understand it there is no concept of a dielectric medium for the vdW term, so I lean towards not including it.

At least in OpenMM world, the incompatibility with Lorentz-Berthelot mixing rules seems to only be in reciprocal space. The docs imply to me that geometric mixing rules are used in reciprocal space no matter what, and that's just an acceptable approximation. From this I'm inclined to treat it as an implementation detail instead of specifying that LJPME cannot ever be used with Lorentz-Berthelot. In fact, GROMACS seems to have no problem doing that.

[mattwthompson]

Thanks all for the reviews - I think I've covered everything brought up, but I'll leave this open for a short period of time in case I've introduced new typos or missed an important detail from our discussion in the meeting