[gmx-users] Multiple torsional parameters

Pedro Alexandre Lapido Loureiro paloureiro at biof.ufrj.br
Wed Aug 20 14:52:01 CEST 2003

> Pedro Alexandre Lapido Loureiro wrote:
> > Hi,
> > 
> > I am implementing the lipid force field of Smondyrev & Berkowitz (J Comp
> Chem 
> > 20, 531 - 1999).
> > The problem is they use two expressions for one dihedral, such as:
> > LC2  LC2O    1  0.0   5.8576   3
> > LC2  LC2O    1 180.0  4.184    1
> > I have built my .top file in this way.
> > When I run grompp, there is a warning saying the former parameters will be
> > overridden and the latter will be used.
> > How can I solve this?
> > (Sorry if a matter like this has been already discussed in the list...)
> 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...



Pedro Alexandre Lapido Loureiro
Laboratório de Física Biológica
Instituto de Biofísica

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