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ReactionMechanismGenerator / ARC

ARC - Automatic Rate Calculator
https://reactionmechanismgenerator.github.io/ARC/index.html
MIT License
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Free rotor in force field? #327

Open xiaoruiDong opened 4 years ago

xiaoruiDong commented 4 years ago

Force field conformer jobs of prenol, 2,3-dimethylbut-2-ene and their radicals, RO2, RO2H, OOQOOH indicates they could possess free CH3 rotors in MMFF94s. Here, I provide an example of prenol. 2D structure image

3D structure image

ARC default conformer torsions result (500 random conformers) image

When applying 10000 random conformers: image

When checking exact dihedral angles for the lowest 5 conformers of both samplings, dihedrals are indeed different (see below). For 10000 sampling, FF_energy are equal; for 500 sampling, the difference only appears at 10th digit after decimal points image

It seems like there is no well for the two alkenyl methyl groups (H3C-C=C). I am not sure about the influence of this kind of behavior. (This may enlarge the conformer search space?). So far I haven't had the ab initio result yet.

xiaoruiDong commented 4 years ago

@mjohnson541 @dranasinghe @fhvermei Not sure have you seen this before?