On Wed, Feb 27, 2013, Marek Maly wrote:
>
> So if one would like to add some improper torsion to group of 4 atoms
> with known Amber atom types,
I don't really agree with the previous answers. There isn't any way to add
such a term as a part of the force field, since tleap will only make improper
terms for a central atom bonded to exactly three other atoms. If you have an
arbitrary group of 4 atoms (that doesn't fit the bonded criterion), you may be
able to treat it as an "NMR" torsion restraint (although the functional form
of a restraint term is not the same as the usual dihedral terms in the force
field.)
The other option is to edit the prmtop file (either manually, or perhaps via
ParmEd) to add in the terms you want.
...good luck....dac
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Received on Wed Feb 27 2013 - 12:30:03 PST
