On Mon, Dec 16, 2013, Meng wrote:
>
> may I ask what is the explicit expression for improper terms in GAFF force
> field? I found papers on GAFF force field, but I did not find explicit
> expression of improper terms in any of them. I dig out the AMBER archive,
> and it was said that improper dihedral terms have the same expression as
> normal dihedral in GAFF. This is confusing to me, because in other polymer
> FF such as CHARMM FF, there is an improper term separate from dihedral term.
What you read is correct: the expression for improper terms in Amber is the
same as for ordinary (proper) torsions. This is indeed different than for
other force fields, such as CHARMM.
...good luck....dac
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Received on Mon Dec 16 2013 - 18:00:02 PST
