[gmx-users] solvation free energy, electrostatic transformation

[Justin Lemkul]

On 7/27/15 10:35 AM, Daniele Veclani wrote:
> OK! I got it
>
> I created the topology with automated topology builder, and I also
> optimized the
> molecule in gaussian, and the charges are similar.
>
> Are there other ways to derive the cherges?
>

GROMOS force fields are very empirical.  The charge derivation starts with a DFT 
calculation of the ESP around the molecule, and charges are assigned that 
approximate that ESP.  That's the extent of the QM.  Everything else is an 
empirical adjustment to fit condensed-phase target data.  This makes GROMOS 
somewhat hard to parametrize (in a sense) because the target data are expensive 
and the charges are assigned empirically (e.g. chemical intuition).

-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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