Re: problem with Dihedral

From: Kenno Vanommeslaeghe (kvanomme_at_rx.umaryland.edu)
Date: Sun Oct 06 2013 - 21:42:57 CDT

I don't know for sure what you mean by 2s+1, but the only thing I can
think of is the QM spin multiplicity. There's no connection between that
quantity and the multiplicity of a dihedral cosine function (except the name).
http://en.wikipedia.org/wiki/Multiplicity_%28chemistry%29
http://en.wikipedia.org/wiki/Spin_%28physics%29#Spin_projection_quantum_number_and_spin_multiplicity

Adjusting force field parameters is highly specialized work; if you're not
sure about the meaning of the force field terms, then you probably
shouldn't go there.

On 10/06/2013 08:27 AM, farzad kiani wrote:
> Hi
> I want to set Dihedral in force filed parameter file
> I don't know what should I set for n:multiplicity
> it is described as 2S+1
> namd user guide says "The ‚Äúmultiplicity‚ÄĚ n is typically 1, 2, or 3,
> although for a
> small number of cases two or three terms with different values of n are
> provided for
> the same atom types."
> I have a case two or three terms with different values of n are exist:
> SI O SI O -0.0100 ?? 180.00
> SI O SI O -0.2350 ?? 180.00
> does anyone know what should I do?

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