[gmx-users] modify C6 directly in FF using sigma and epsilon

[David Mobley]

David,

I'm using 3.3/3.3.1.

Is there an easy tweak to the source code that would allow something
like this? i.e. could I somehow easily tweak the bit where it reads
the nonbond_params section so I can use an alternate combination rule
there by specifying, say, a different nonbonded parameter type?

Thanks,
David


On 4/5/07, David van der Spoel <spoel at xray.bmc.uu.se> wrote:
> Ryogo Sugitani wrote:
> > David,
> >
> > How about adding [ nonbond_params ] in your ff???nb.itp file
> > as shown in p.88 of the user's manual?
> > I believe it will override the default vdw interaction for that
> > particular atom-type pair.
> > (Assuming you want to use combination rule #1 just for that atom-type pair)
> >
> > If I miss your point, please disregard this...
> >
> >
> In gromacs 3.3 it will still use the same combination rule. However, in
> older versions, possibly 3.2.1, this would work: use sig/eps for
> generating a matrix and overriding it with C6/C12. We took that out
> because it is hard to explain, and we thought it was unnecessary...
>
> --
> David.
> ________________________________________________________________________
> David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
> Dept. of Cell and Molecular Biology, Uppsala University.
> Husargatan 3, Box 596,          75124 Uppsala, Sweden
> phone:  46 18 471 4205          fax: 46 18 511 755
> spoel at xray.bmc.uu.se    spoel at gromacs.org   http://folding.bmc.uu.se
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