2021-01-22 Meeting notes

30 min

Update with fitting to larger hydrocarbon set

Trevor

• new fitting we larger set, ~170 molecules, mainly AlkEtOH

• Gradients are now an objective, no hessians(?)

• Rest of procedure is similar as before

• CBn: Why one conformer per molecule?

• TG: Molecules are small, that is why only one conformer. Standard settings for conformer generation

• CBy: What is the purpose of 3-4 Ang cutoff in the conformers?

• TG: For the simple molecules only small number of molecules came out.

• CBy: Relative energy differences between conformers are informative. Why only few alkenes, but many alkanes

• TG: This is what is in the dataset (Alketoh)

• CBy: The parameters (slide 3) are two categories. One that have enough data, and the ones that don’t.

• Splitting of a1 is important, same result as last time. It is split multiple times. See slide 4

• four membered rings seem to drive the splitting here, see splits 4,5,6

• CBn: Can your method recover something where we exactly know the result?

• TG: Something I’m working on. Will do later, needs lots of compute.

• CBy: SMARTS strings representation seems to be very specific for dataset. They will fail badly with other molecules.

• Looking at “variances” of the parameters.

• Splitting of a1 reduces number of bits-represented and No. of primitives

• CBn: Additional parameters will almost always make ff better in the training set. Will be specific for the training set

• DM: Might try to evaluate FF on validation set during the fit

• slide 6: not completely clear how the scoring works right now. Needs some more clarification

• DM: Maybe a small write-up would be helpful

• TG: Yes, good idea. Was planning to do so.

• CBy: The amount of possible splits and chemistry is very huge. Can you find common chemistry in splits. Need a way to divide space in an informative way.

• Next steps: only alkane dataset, make a case where we know the answer and see if we arrive there. Start with one bond and one angle. generally improve experimental design.