[gmx-users] Coulomb and vdW energies

[Justin Lemkul]

On 12/1/19 5:28 AM, Shreyas Kaptan wrote:
> Hi.
>
> I would not say that it is completely unrealistic/unphysical. Especially,
> the Electrostatic part. If within two subgroups, you could show that there
> is systematic repulsive or attractive potential, that could lead to some
> hypothesis about how they interact (e.g. pushing/pulling). Of course, this
> is only true of ratios of decomposed energies that are large proportions of
> the total energy, as smaller portions might not be really
> significant indicators of strong interactions.

I would argue that such an outcome is equally likely to be an indicator 
of a force field error as it is some real behavior. The problem with all 
such decomposition is - there is no verifiable target data (QM or 
empirical) that can tell you which is true. This is why the individual 
quantities have no meaning. Total interaction energy is a quantity that 
you can get from QM very easily and is therefore valid target data - 
CHARMM uses this and the origins of OPLS were the same. Other force 
fields do not necessarily target such information so the total 
interaction energy with those models is questionable.

-Justin

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Justin A. Lemkul, Ph.D.
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