Try adding the lines in the datafile
X extra bond per atom
X extra angle per atom
X extra angle per atom
X is a number based on the topology of the molecule.
The last line may not be necessary if u dont have dihedrals .
Lammps needs to keep track of 1 2 , 1 3, 14 neighbours.
Hope it helps
Arun
Thanks Arun, but I am already adding extra angle and bond per atom.
create_box 4 total bond/types 2 angle/types 4 dihedral/types 4 extra/bond/per/atom 6 extra/angle/per/atom 7 extra/special/per/atom 6
The problem is that I do not understand the atom types I should use in molecule template file as I mentioned above.