[gmx-users] Amber03ws includes an unexpected dihedral with atoms -C N CA CB

[Ramon Crehuet]

Dear all, 
I would like to use the Amber03ws force field described in Best, Zheng and Mittal, J. Chem. Theor. Comput., 10, 5113-5124, 2014. 
This force field is contributed in http://www.gromacs.org/Downloads/User_contributions/Force_fields 
When using it, Gromacs reports a warning about a CB atom in GLY residues. I could trace it to the aminoacids.rtp file, which contains these lines for the GLY residue: 
[ dihedrals ] 
CA C +N +H 
O C +N +H 
-C N CA CB 
-C N CA C 
CA C +N +CA 
O C +N +CA 
-C N CA HA1 
-C N CA HA2 
HA1 CA C +N 
HA2 CA C +N 

The presence of the CB atom is an error? Can I simply ignore this warining? 

Thanks, 

Ramon