Re: charmm and dihedral multiplicity

From: Vani Krishna (vakri2002_at_yahoo.com)
Date: Fri Dec 17 2004 - 18:46:04 CST

>
> > Hello all,
> >
> > I am confused about dihedral multiplicity.
> >
> > It seems to be that the multiplicity value
> indicates that a number of
> > identical dihedrals exist and this is a time
> saving measure:

I may be wrong, but these are my thoughts regarding
multiplicity:

In AMBER, the multiplicity is because of the reason
mentioned above. But that is not so in CHARMM. In
CHARMM, multiplicity refers to the number of minima
between 0 and 360 in the variation of energy-angle
plot for the torsional potential. this concept is
especially useful if the torsional potential is not
exactly sinusoidal, so each minima can be associated
with a different force constant (related to barrier)
and that would describe the torsional profile more
accurately.

                
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