Re: [AMBER] "istrng" option in MMPBSA calculation

From: Jason Swails <>
Date: Thu, 18 Oct 2012 08:00:50 -0400

On Thu, Oct 18, 2012 at 6:57 AM, baogen duan <> wrote:

> Dear Amber users and developers´╝Ü
> In the course of calculaiton of electrostatic solvation free energy
> using MMPBSA script, the default value for "istring" option is 0, but it is
> set 0.2M. whether does it mean that the solvated and reference state for
> solvation energy calculation both in 0.2M ion strength condition? Or
> solvated state is in 0.2M condtion. But the reference state (vacuum
> condtion) is no ions. Thanks in advance!

The vacuum condition has no ions. The free energy you are calculating is
transferring from vacuum into a solution with an ionic strength of 0.2M.


Jason M. Swails
Quantum Theory Project,
University of Florida
Ph.D. Candidate
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Received on Thu Oct 18 2012 - 05:30:03 PDT
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