Jinyao Wang wrote: > gmx-users， > Dear all, > > I make a *.itp for benzene by myself. All parameters come from the > ffoplsaabon.itp and ffoplsaanb.itp. while I have some puzzled about the > dihedral parameters of benzene.
You should check out the literature of OPLS/AA and see how aromatic rings are intended to be treated. Basically, if you're using improper dihedrals to enforce planarity, you probably don't want any other dihedral potentials. > In ffoplsaabon.itp file, there are > dihedral parameters of benzene and the potential function is 3, like > this: > ;X CA CA X 3 30.33400 0.00000 -30.33400 0.00000 0.00000 0.00000 ; > aromatic ring The semicolons make this whole line a comment, which is consistent with not wanting both proper and improper dihedrals here. > but for improper dihedral of benzene there is some another dihedral > parameters of benzene and the potential function is 1,like this: > ; Z -CA-X -Y improper torsion. CA is any ring carbon > > #define improper_Z_CA_X_Y 1 180.0 4.60240 2 > > I think the improper dihedral can keep the molecule of benzene planar. > So I have no idea how to set dihedral the parameters of benzene. You won't be sure until you've read the primary literature. Mark _______________________________________________ gmx-users mailing list [email protected] http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to [email protected]. Can't post? Read http://www.gromacs.org/mailing_lists/users.php
