[gmx-users] question about convert Ryckaert-Bellemans dihendral to dihendral type 9

[张敏华]

Dear all:
        I am trying use antichamber to generate an tpr file for a special residue. When I got the converted tpr file, I noticed that the "func" in [dihendral] is 3, that means it is a Rychaert-Bellemans dihendral. But the Amber03 forcefield use dihendral type 9(func 9). So does anyone knows how to convert Rychaert-Bellemans dihendral to dihendral type 9? I calculated the charge of this special residule by gaussian and fitted into RESP charge, then converted it to topology file in Amber forcefield.  I have encountered an fatal error when I using pdb2gmx, which tells me that residues in one molecule have a different 'dihendrals' type: 9 and 3. 
        I would appreciate any advice!
        Best,


Minhua Zhang
Institute of Plant Physiology and Ecology, SIBS, CAS
mhzhang01 at sibs.ac.cn