Re: force constant from gaussian to namd

From: Mark Abraham (
Date: Wed Sep 20 2006 - 14:00:05 CDT

Shenoy, Sukesh wrote:
> I need to convert the force constants given in gaussian to use it in NAMD.
> 1) Can anybody tell me what units of force constants given in the gaussian
> output file?

You could try looking in the Gaussian documentation for this.

> 2) How to convert the force constants from gaussian to use in NAMD i.e.
> kcal/mol/A02 or kcal/mol/rad2 for bonds and angles respectively.

The same way you'd convert any other physical quantity from one
dimension to another...

There is also no reason to expect the resulting force field (i.e. model
physics) to be a reasonable model of either Gaussian physics, or real
physics. It sounds like you need to do a lot more background work before
you attempt to modify a force field in a useful fashion. A good start
would be the tutorial on the topic available from the NAMD web page.


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