OPLS mixing rules

From: fett_at_vtr.net
Date: Tue Apr 06 2010 - 09:40:05 CDT

Dear Namd Developer:
A quick question:

I am using the OPLS force field (converted to CHARMM format)and I have
noticed that Rmin values for the VDW potential are expressed as Rmin/2, if I
understand properly OPLS mixing rules use the geometric mean for sigma
(Rmin) and epsilon, therefore why the Rmin values are expressed as Rmin/2 if
those values are only needed for the arithmetic mean (CHARMM mixing rules)?

Is the NAMD code converting those Rmin/2 values to Rmin or sigma when the
vdwGeometrcSigma option is activated?

If somebody could point me in which part of the source code is this feature I
could have a look by myself.

Best

Jose Antonio Garate

  

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