[gmx-users] Multiple torsional parameters

[Pedro Alexandre Lapido Loureiro]

> > >You are probably defining two dihedral *types* for the same pair of
> atoms.
> > >That won't work. What you will need to do, is add another dihedral to
> the
> > >.rtp, .itp or .top of your lipid, and specify explicit parameters (or an
> > >explicit type, like in the G43a* ff's) for both of them.
> > >
> > Thank you, Anton
> >
> > but that`s exactly what I have done. My .top file is an "explicit type"
> > topology file, as long as it contains all the parameters of the force
> > field. Those two lines I have "pasted" above are from my lipid.top file.
> > And it did not work...
> >
>
> Dear Pedro,
> Try this in your molecule.itp:
>
> [dihedrals]
> 1  2  3  4    values_A
> 1  2  3  4    values_B
>
> 1 2 3 4  are the numbers of the atoms involved
>
Thanks, Anton, Marcos and Yuguang Mu!

Yes, it works. 
The problem was my .top file includes the entire forcefield.
So for this to work I had to comment the lines refering to the dihedrals (in 
the ".rtp-like" part of my .top.
Thanks again! 


Cheers,
Pedro.

--
Pedro Alexandre Lapido Loureiro
Laboratório de Física Biológica
Instituto de Biofísica
UFRJ
Brasil