[gmx-users] CHARMM36 for GMX

[Justin Lemkul]

On 8/2/17 2:18 PM, Alex wrote:
> Hi all,
> 
> I am not entirely sure it's a question for the Gromacs community, as this
> is regarding CHARMM36, but it appears that the original forcefield is fine,
> while I am confused by its Gromacs version.
> 
> Namely this: the MacKerell website distributes a Gromacs version of
> CHARMM36 where ffnonbonded.itp has pretty much all default charges set to
> zero. Is this called for??
> 
> I apologize in advance if this is a dumb or misdirected question, as I've
> never worked with CHARMM before.
> 

Charges in ffnonbonded.itp are never used by any force field.  It's nothing to 
do with CHARMM, just a relic of old GROMACS formats and likely a desire to 
catalog "default" charges for certain groups.  But they serve no functional purpose.

-Justin

-- 
==================================================

Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

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