[gmx-users] convert an itp from gmx to olps?
lindahl at stanford.edu
Fri Sep 6 19:09:45 CEST 2002
nicolis at guideo.fr wrote:
> I have an .itp topology of a small drug for the gmx forcefield and I want to
> convert it to use the opls.
> What sections should I change in addition of changing the atom types?
> I know there are different definitions for the planarities (no impropers in opls
> but dihedrals with a periodicity of 2?) but what about the bond and angle
> Thank you,
That depends on how you created your itp file; if you haven't added any
explicit parameters (i.e. they are looked up based on the atom types) it
might suffice to:
1. Add the hydrogens
2. Change atom types to OPLS ones
3. Remove chiral-center improper dihedrals
4. Change proper dihedrals to type 3.
You might also want to change planar group impropers to OPLS dihedrals
with a periodicity of 2, but I can't imagine that will affect things too
Why not post the topology - then I can probably recommend what to do
with it :-)
More information about the gromacs.org_gmx-users