reaxFF for graphene

There are also several issues with your input script:

  1. Your second “read_data” command creates a graphene-like lattice of hydrogen atoms instead of carbon ones, because you used an offset, which changed the type of created atoms from 1 to 2. Even after correcting this the structure will deform, because there are unsaturated atoms on the edges. You have to either fix them or apply periodic boundary conditions.

  2. Parameter files for reaxFF shipped with LAMMPS are written for units real and using different ones will lead to errors.

  3. Using fix npt for the z direction may be tricky, because the simulation box can easily shrink to the point when an atom will interact with itself across the boundary.

Michal

You can also try changing your pdamp parameter. It may also cause this problem.