[lammps-users] Compass parameters in lammps

The msi2lmp tool has been upgraded recently (past 2 years) to maintain consistency with LAMMPS. However, it requires a force field parameter file in the Discover format (.frc). Such files for CVFF and others are included in msi2lmp. To use msi2lmp with COMPASS atom types and parameters, you would have to create a similar .frc file.


> Date: Fri, 28 Aug 2009 08:12:53 -0600
> From: Steve Plimpton <[email protected]>
> Subject: Re: [lammps-users] Compass parameters in lammps
> To: audupa@…132…
> Cc: lammps-users@…396…sourceforge.net
> Message-ID:
> <33ea1b0a0908280712h2a9746e6j780e96dfcd39ffe8@…25…>
> Content-Type: text/plain; charset=ISO-8859-1
> In general, you need a tool that transforms Mat Studio output
> (including its COMPASS ff assignments) to LAMMPS input.
> Msi2lmp is meant to be that tool, but it is old. If it is not
> working, then you (or someone) will need to modify it to
> work with the current Mat Studio product. This also assumes
> you have the COMPASS param files provided with Mat Studio,
> which msi2lmp simply reads. Those param files
> are proprietary and are not part of LAMMPS.
> Steve
> On Wed, Aug 26, 2009 at 10:26 AM, <audupa@…132…> wrote:
> > Sir,
> >
> > ?I am a new user to lammps. My research group and I use the COMPASS force-field in
> > our simulations.
> > ?We use Material Studio to build the initial configuration. We then use the
> > msi2lmp tool in LAMMPS so that we can run the simulation in LAMMPS. This tool does
> > not have COMPASS parameters built in it. Hence my research group is manually
> > altering the output file.
> > ?We have managed to get the COMPASS parameters for simple atoms like Carbon and
> > Hydrogen after going through some papers. It would be of great help to us if you
> > could advice on how we can get the COMPASS parameters for all/many more atoms.
> >
> > Thanks,
> >
> > Anirudh Udupa
> >
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Dear Anirudh

I may be a little late in replying. The Compass force field is not open (propriertry, Accelyrs). You can use it Material Studio but not in Lammps. The closest which matches with COMPASS is PCFF force field which is open. If you want to only use COMPASS, you have to extract each and every parameter from the MS seperately which is also quite tricky. In any case, if you come up with something, please do let me know.