[lammps-users] fix rigid and periodic boundary

Dear all,

Just to check if my interpretation is correct or not. I’m setting each molecule in the box to be a rigid body. But I’m not sure if the rigid-body molecules cam be divided into two parts by the periodic boundary conditions in the input file of initial coordinates. I run a simulation with several molecules cut by the boundary at the beginning, but the result looks very weird and the molecules around the boundary keep being elongated throughout the simulation. So my interpretation is that each rigid-body molecule should be kept as a whole in the input file. Is it correct?

Thank you

From the fix rigid doc page:

If the atoms in a single rigid body initially straddle a periodic
boundary, the input data file must define the image flags for each
atom correctly, so that LAMMPS can "unwrap" the atoms into a valid
rigid body.