[gmx-users] Grompp Error (No default Ryckaert-Bell)

[Dongsheng Zhang]

Hello, everyone,

I am using oplsaa force field for my peptide Ace-(MET)5-NMet. During
grompp, I get two warnings:

WARNING 1 [file "Met5Peptide.top", line 620]:
  No default Ryckaert-Bell. types, using zeroes
WARNING 2 [file "Met5Peptide.top", line 820]:
  No default Ryckaert-Bell. types, using zeroes

After I check Met5Peptide.top, I found those two dihedrals are:

CH3(ACE)-C(ACE)-N(MET)-CA(MET)
CA(MET)-C(MET)-N(NAC)-CH3(NAC)

By translation, those dihedrals are the same, it will be (in
ffoplsaabon.itp):
CT  C  N  CT_2


When I check ffoplsaabon.itp, I can't find any entry for CT  C  N  CT_2,
therefore it seems I have to add RB coefficients for this dihedral by
myself. Could anyone give me a suggestion about the numerical values for
those coefficients?

Thanks in advance!


Dongsheng






-- 
Dongsheng Zhang <dong at pampas.chem.purdue.edu>