[gmx-users] CHARMM36 for GMX

[Alex]

Huh. Most of my work has been with OPLS-AA, so I took that for granted.
Where would the actual charges be, then?

Alex

On Wed, Aug 2, 2017 at 12:32 PM, Justin Lemkul <jalemkul at vt.edu> wrote:

>
>
> 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
>
> --
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> Justin A. Lemkul, Ph.D.
> Ruth L. Kirschstein NRSA Postdoctoral Fellow
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> jalemkul at outerbanks.umaryland.edu | (410) 706-7441
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