Dear all,
I am trying to work on a MD simulation of ionic salt solutions. Some of the papers I came across have modeled the interactions considering ionion pair potentials. However, for a specific salt, sodium sulphate, interaction parameters between sodium ion and sulfate ion have been described. I am a little confused about the modeling of the sulfate ion. When considering such a potential model, the sulfate is treated as a single site (with all SO) interactions being neglected. While the pairpotentials typically represent atomatom interactions, modeling an interaction where one of the sites is an ionic radical is a little unclear to me. Any suggestions on how to model the sulfate as a single site using LAMMPS would be really helpful.
Thank you.
Ganesh

Can you state the specfic interaction (e.g.a formula) that
you don't see how to do in LAMMPS?
Steve
Dear Steve and Lammpsusers,
The issues I am trying to solve are—
1. Two interaction potentials are superimposed, namely, Sutherland potential (infinite repulsion for r<=sigma, and LJ attraction for r>sigma) and twoYukawa potential. While I was able to modify the Yukawa potential in Lammps to apply the latter, any suggestions about the short range potential (Sutherland) would be helpful.
2. When modeling Na+ and sulfate ion interactions, in the pair coeff command should the i and j values correspond to that for Na and S ? All SO interactions are neglected here. Should some other restriction be imposed on the sulfate so that Lammps knows that NaS interaction is actually Nasulfate interaction?
Thanks
Ganesh
— On Mon, 27/7/09, Steve Plimpton [email protected] wrote:
> From: Steve Plimpton <sjp[email protected]…33…24…>
> Subject: Re: [lammpsusers] Representing an ion
> To: “Ganesh” <[email protected]…545…>
> Cc: “Lammps Users” <[email protected]…38…ists.sourceforge.net>
> Date: Monday, 27 July, 2009, 7:52 PM
>
> Can you state the specfic interaction (e.g.a formula) that
> you don’t see how to do in LAMMPS?
>
> Steve
>
> On Fri, Jul 24, 2009 at 10:46 AM, Ganesh<[email protected]…1418…> wrote:
> >
> > Dear all,
> >
> > I am trying to work on a MD simulation of ionic salt solutions. Some of the
> > papers I came across have modeled the interactions considering ionion pair
> > potentials. However, for a specific salt, sodium sulphate, interaction
> > parameters between sodium ion and sulfate ion have been described. I am a
> > little confused about the modeling of the sulfate ion. When considering such
> > a potential model, the sulfate is treated as a single site (with all SO)
> > interactions being neglected. While the pairpotentials typically represent
> > atomatom interactions, modeling an interaction where one of the sites is an
> > ionic radical is a little unclear to me. Any suggestions on how to model the
> > sulfate as a single site using LAMMPS would be really helpful.
> >
> > Thank you.
> >
> > Ganesh
> >
> > ________________________________
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> >
> > _______________________________________________
> > lammpsusers mailing list
> > [email protected]
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> >
> >
