Link to the discussion on missing torsion parameter for dialkyl amide: https://openforcefield.atlassian.net/wiki/x/AwDMEw
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Around 3562 torsions in the first gen training set were assigned to t69, which indicates that there’s a possibility that the parameter is overly general.
There are outliers which are supposed to be around 0 degrees but rotate to 180 degree during MM optimization (or 180->0)
(3) fitting child parameter candidates
SMIRKS ID | SMIRKS | Initial k | Final k |
|---|---|---|---|
t69 | [*:1]~[#7X3,#7X2-1:2]-!@[#6X3:3]~[*:4] | 1.0 | 0.978 |
t69a candidates | [*:1]-[#7X3H0:2]-!@[#6X3:3]=[#8,#16,#7:4] Cf.) t70: [#1:1]-[#7X3:2]-[#6X3:3]=[#8,#16,#7:4] | 1.0 | 1.27 |
1.5 | 1.64 | ||
2.0 | 1.68 | ||
[*:1]~[#7X3H0:2]-!@[#6X3$(*=[#8,#16,#7:4]):3]~[*:4] | 2.0 |