intprt option in Thermodynamics integration

From: Marcela Madrid <>
Date: Wed 10 Jan 2001 20:51:22 -0500


I am repeating the example from Gibbs of charging a sodium ion
in a box of water. "Intprt" determines which
energies contribute to the free energy calculation. I am setting
which means no
intra-perturbed group energies are accumulated. I would have
expected in this case to get the same results regarding of
the value of intrprt, since the perturbed group is only one ion, as
in the file PATNRG:

Group legend: (Group #:atom #:res #:atom_name)
    1: 1: 1:NA //
 ***> Total number of groups defined = 1

However, the free energy difference when intprt=0 is exactly zero. Why
are the interactions between the ion and the solvent not taken into
in this case?

thanks, Marcela
Received on Wed Jan 10 2001 - 17:51:22 PST
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