Re: sodium ion in water

From: Axel Kohlmeyer (
Date: Thu Aug 11 2011 - 00:36:08 CDT

On Thu, Aug 11, 2011 at 1:17 AM, divya nayar <> wrote:
> Hi,
> I want to simulate one sodium ion in 255 molecules of water (SPC/E).  The
> ion will be considered as charged Lennard Jones sphere and I am using
> Dang-Smith paramters for the sodium ion. I would like to ask, what should I
> do to define a compensating electric field for my system because my system
> is not neutral?

you don't need to do anything. the compensating charge
will follow automatically from using long-range electrostatic
with PME.

> Can anyone suggest on the above or some reference ?

any textbook on MD that explains ewald summation and
PME should be a sufficient reference. the compensating
charge is a side effect of ignoring the non-periodic term
at k=0.


> Thanks
> Divya

Dr. Axel Kohlmeyer
Institute for Computational Molecular Science
Temple University, Philadelphia PA, USA.

This archive was generated by hypermail 2.1.6 : Mon Dec 31 2012 - 23:20:41 CST