Re: Interaction energy definition

From: Aron Broom (
Date: Fri Nov 22 2013 - 14:57:35 CST

The interaction energy is the sum of all the pairwise potentials that would
be calculated when doing MD. So for water and protein that will be the sum
of all the pairwise VDW, and electrostatic terms between all pairs of
water-protein atoms.

Since that interaction energy in a vacuum would be 0, I suppose you can
make the argument that there is some relation to the solvation enthalpy,
but the problem is that you're ignoring any changes in protein-protein
enthalpy that might happen as a result of being solvated.

Anyway, the main point here is that the interaction energy is very
precisely defined in terms of forcefield potentials, but interpreting what
that means is something else.

On Fri, Nov 22, 2013 at 3:45 PM, nan li <> wrote:

> Hi all,
> I am using pair interaction energy calculation to get the "interaction
> energy" between water and protein in a system. I am confusing about the
> definition of "interaction energy". Is it the enthalpy of solvation?
> DeltaH= Delta H{lattice energy} + Delta H {solvation}.
> or is the "interaction energy between water and protein" the mixing
> enthalpy DeltaH?
> Also, if the interaction energy is for protein-ligand interaction, is the
> interaction energy the mixing enthalpy?
> Many thanks.
> Nan

Aron Broom M.Sc
PhD Student
Department of Chemistry
University of Waterloo

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