[gmx-users] Mixing Force Fields

Fabian Casteblanco fabian.casteblanco at gmail.com
Fri Oct 14 17:23:01 CEST 2011

Hello community,

I have a general question about mixing force fields.  I want to try to
use CGenFF to model the drug and I wanted to use CHARMM for the
solvent.  I see the general advice given online is to always use only
one forcefield but I know CGenFF was developed off CHARMM but
specifically for drugs.  If anything, I would like to try it to see
how different results are from just using CGenFF.  How would one go
about using two forcefields on your topology? For example below, would
one simply add the non-default FF to the default FF?

;	File 'topol.top' was generated
;	By user: Administrator (500)
;	On host: fabian-3bef2d6a
;	At date: Fri April 1st 02:59 PM 2011
;	This is your topology file
;	DRUG SOLUTION w/ Ethanol

; Include forcefield parameters
#include "Charmm.ff"
#include "Cgenff.ff"

**Thanks for everyones help.

Best regards,

Fabian F. Casteblanco
Rutgers University --
Chemical Engineering PhD Student
C: +908 917 0723
E:  fabian.casteblanco at gmail.com

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