Dear GMX users, I'd like to use oplsaa FF format to build my own force field for my project. After I finished it, I can use pdb2gmx. but not grompp. The problem is from my **nb.itp file. I have specified some unusual (not follow the combination rule) nonbonded interaction parameters after [ atomtypes ] section as follows:
[ nonbond_params ] ; i j func sigma epsilon CT CT 1 3.80000e-01 2.09200e-01 When I run grompp, the program complains that atom type CT is not found. If I change CT to opls_182, then it works fine. However, when I check oplsaabon.itp, CT is used, but not opls_182. Could anyone tell me why I can't use atom type in *nb.itp? How can I fix it? If opls_182 is defined as atom type, then how does gromacs recognize CT is **bon.itp? By the way, my question relates to my previous question. Unfortunately, no one answered it. I really appreciate someone can help me. The following is my previous email: In ffoplsaanb.itp, there are 8 columns. ; name bond_type mass charge ptype sigma epsilon opls_001 C 6 12.01100 0.500 A 3.75000e-01 4.39320e-01 ; SIG In ffG53a5nb.itp, there are 7 columns. [ atomtypes ] ;name at.num mass charge ptype c6 c12 O 8 0.000 0.000 A 0.0022619536 1e-06 Could anyone tell me how gromacs knows to read 8 columns for oplsaa FF, but 7 columns for gromos FF? Thanks! All the best! Dongsheng _______________________________________________ gmx-users mailing list gmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users 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