[gmx-users] proper dihedrals

[David van der Spoel]

On Fri, 2004-01-30 at 12:28, Milton Taidi Sonoda wrote:
> Anton Feenstra wrote:
> 
> > Milton Taidi Sonoda wrote:
> >
> >> Is there a way to model a proper dihedral
> >> as a sum of two or more terms of the expression
> >> 4.52 of the gromacs user manual using the
> >> [ dihedraltype ] section?
> >
> >
> > Yes, simply add as many as you want for a given set of atoms.
> > This will work for .itp/.top files, but may not work in .rtp files
> > for all versions.
> >
> Anton
> 
> I've tested your advise but the results were not the
> expected, at least for the .itp file.
> 
> I've created a new test ff with the dihedraltypes as
> 
> ...
> [ dihedraltypes ]
> 
> CT   CT   CT   CT   1   180.0  15.0  3
> CT   CT   CT   CT   1   180.0  15.0  2
> ...
> 
> in fftestebon.itp file.
> However, when processing the parameter files I've got
> 
> ...
> WARNING 1 [file "/usr/local/gromacs_mp/share/top/fftestebon.itp", line 12]:
>   Overriding Proper Dih. parameters,
>   old: 180 15 3 0 0 0
>   new: CT   CT   CT   CT   1   180.0  15.0  2
> ...
> 
> I've tried different file formats such as
> 
> ...
> [ dihedraltypes ]
> CT   CT   CT   CT   1   180.0  15.0  2    180.0  15.0  3
> ...
> 
> but gromacs only interprets the firsts four numbers.
> Where did I mistake?

don't do it in the types, but in the topology, i.e.
[ dihedrals ]



> 
> Milton Taidi Sonoda
> 
> 
> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assist. 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://xray.bmc.uu.se/~spoel
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