Dear EB, Many thanks for the kind reply! We have revised the improper section followed your advice. The force field is amber99sb. Unfortunately, the program complained again, "No default proper dih. types'. Any advice? Thanks!
Cheers Jeremy --------------- Hi Jeremy, I have checked how improper dihedral should look like in Amber, guessing that you used amber99sb force field. But I am wondering from where the improper in your ligand.itp was generated. As it doesn not look alike with the amber force field. It actually is not the problem of multiplicity but the number of parameters that you put in the improper is not enough. It should be at least three parameters in the improper section Yours look like [ impropers ] CAD OAX CAB CAG 0.000 167.4 (two parameters here angle and force constant) Whereas the program is looking for CT CT OS CT 9 0.0 1.60247 3 (here function, angel, force constant and multiplicity??) copied from the amber bonded force field parameter :) I think you should generate a logical itp file which fullfil all the necessary requirements before you run you simulation. Cheers, EB -- gmx-users mailing list [email protected] http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/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/Support/Mailing_Lists
