[gmx-users] Regarding energy calculation of head groups

[Justin Lemkul]

On 3/11/16 12:20 AM, Raju Lunkad wrote:
> Dear all Gromacs users,
> I wanted to calculate the enthalpy of headgroups of the surfactants. In
> "mdp file" I have mentioned the energy as N4_O2 (Surfactants head groups)
> but I am getting the following error:
>
>   atoms 1 and 4 in charge group 1 of molecule type 'BTM' are in different
> energy groups
>
> I am not sure but in my opinion,  the error is coming because of the N4
> contains  -0.5 charge and O2 contains -0.7 charge.
> Kindly tell me how to mention energy groups in "mdp file" with charged
> atoms.
>

The error has nothing to do with charge.  The energygrps you defined are 
splitting a charge group, which is not something you can do.  I also don't know 
what value there would be in calculating the enthalpy of part of a larger 
molecule, but that's for you to decide...

-Justin

-- 
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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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