Error in ion.mdp command

User discussions
1

GROMACS version:
GROMACS modification: Yes/No
While performing ions.mdp command
“gmx_mpi grompp -f ions.mdp -c solv.gro -p topol.top -o ions.tpr”

i have recieved following error,
ERROR 1 [file UNK.prm, line 71]:
Encountered a second block of parameters for dihedral type 9 for the same
atoms, with either different parameters and/or the first block has
multiple lines. This is not supported.

ERROR 2 [file UNK.prm, line 72]:
Encountered a second block of parameters for dihedral type 9 for the same
atoms, with either different parameters and/or the first block has
multiple lines. This is not supported.

how to rectify it

2

Your ligand topology specifies dihedral parameters for a torsion that is already part of the force field. That means you generated the topology with a CGenFF version that differs from what is in the force field.

3

So what is the possibility of solving this error

4

You need to use a consistent CGenFF version. You haven’t provided us with any meaningful information about how you generated the topology, which CGenFF version you’re using (in that topology and/or in the CHARMM36 port that supports it), so there’s nothing else anyone can tell you. Force field versions have to be consistent.