[gmx-users] No default Ryckaert-Bell. types for proline

[Kevin C Chan]

Dear Users,

I am testing with OPLSSaa force-field of proline. First I arbitrarily
extract a single PRO from a pdb and fed into pdb2gmx. The resulted gro and
top are however not suitable for further grompp (even minimization). The
error messages are as follows:

ERROR 1 [file topol.top, line 161]:
  No default Ryckaert-Bell. types

When I look into the line 161, it refers to a dihedral term concerning (CD
N CA C) which is not able to be found in ffbonded.itp. However, other
dihedral terms such as (CD N CA CB) or (CD N CA HA) which are also not
found in itp do not report such error and I was successful to grompp after
commenting out the line 161.

Why would this happen?


Thanks in advance,
Kevin
City University of Hong Kong