I use Tersoff and Vashishta potentials which come with LAMMPS to describe interatomic interactions between Si and C.
A box including SiC is equilibrated under PBCs at room temperature. while using Tersoff potential, everything is fine, however, when i use Vashishta potential, atoms start flying. The point is that i use "exactly the same script" (except for the potential function) for both simulations.
I have attached two snapshots which show the situation.
I wonder if anybody can tell me why this happens, and if there is any solution for it.