How did you calculate the cohesive energy for graphite with REBO? Did you use a single sheet or multiple sheets of graphite? If you used multiple sheets and didn’t have some sort of LJ potential keeping them separated you might have some problems.
�� I used a single sheet of graphite. I calculated the cohesive energy by running energy minimization (cg) to dump the total potential energy and then divided the total potential energy by the number of atoms. I also used a compute pe/atom to make sure each individual atom had an energy equal to this cohesive energy.