[lammps-users] dihedral check issue on epoxy group

Dear LAMMPS users

I built up a molecular system with epoxy groups, but the epoxy groups can not pass the dihedral check in LAMMPS. The error message is as follows.

ERROR on proc 17: Invalid atom ID in Dihedrals section of data file (…/atom.cpp:1167)
Last command: read_data gr_epoxy_channel_lmp.data

I believe the problem is here, and below is the one line of dihedral list in the data file.

8650 8 1313 1282 1295 1313

I think the LAMMPS program regarding the dihedral is invalid because the 1 and 4 atoms have the same ID.
However, the dihedral in the epoxy group really has the same oxygen atom on position 1 and 4.

Is there any way to skip this problem?


A dihedral definition with such a shared atom makes no sense. Its dihedral angle cannot change.