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Re: [lammps-users] Water Adsorption Force Field
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Re: [lammps-users] Water Adsorption Force Field


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Fri, 27 Apr 2018 12:16:44 -0400

On Fri, Apr 27, 2018 at 10:44 AM, Jon Wilson <jonwils@...2437...> wrote:
> Hi,
>
> I am trying to model adsorption of water on metal surfaces for
> electrochemical simulations. There is a particular force field I want
> (Siepmann et al. J. Chem. Phys. 102 (1), 1 January 1995) which involves
> computing an angle force based on water dipole vector relative to the vector
> normal to the metal surface. The purpose of this term is to rotate the water
> to face hydrogen-upward.
>
> There is another 3-body term which involves computing a force based on the
> Metal-Metal to Metal-Oxygen bond angle for each of the adjacent surface
> metal atoms (so 6 3-body interactions for 111)
>
> Is there a way to do either of these things in LAMMPS without coding a new
> force field?

no. this requires c++ programming and if you want to have an efficient
implementation, you need to study some many-body pair styles and
tip4p/cut carefully, as they have coding constructs, that are similar
to what you need.

axel.

> I thought about using 'fix angle_style table' for the 3-body
> term but I am not sure how to build a list of surface metal atoms adjacent
> to the metal which has the adsorbed water molecule.
>
> Thanks for your time.
> Jon
>
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-- 
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.