[gmx-users] FEP w/ monovalent ion

[Berk Hess]

>From: "David L. Bostick" <dbostick at physics.unc.edu>
>Reply-To: Discussion list for GROMACS users <gmx-users at gromacs.org>
>To: gmx-users at gromacs.org
>Subject: [gmx-users] FEP w/ monovalent ion
>Date: Fri, 10 Jun 2005 20:15:01 -0400 (EDT)
>
>
>Hello,
>
>I wish to charge/discharge a monovalent ion in order to do a FEP study. I
>know that in the current CVS code, the ewald contribution to the free
>energy is now computed. However, are corrections to the net charge now
>implemented to remove the effect of the "neutralizing plasma" inherent to
>ewald, as I vary the rxn coordinate, lambda, from 0->1 in tinfoil boundary
>conditions?

Determining ionic solvation free energies is very tricky business,
experimentally as well as theoretically.
Last week I heard a talk by P. H. Hünenberger who explained
all the proper corrections you need to make for different electrostatics
treatments to obtain the correct energy. For PME several corrections
are required (most of which are not in the code).

Berk.

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