Parametrization of a reactive many-body potential for Mo-S systems

We present an interatomic potential for the Mo-S system based on the second-generation reactive empirical bond-order formalism. An analytic function is introduced to the bond-order term to capture the effect of the coordination number on the binding energy. The fitting scheme used for this potential is optimized by appropriate selection of the functions, training databases, initial guesses, and weights on each residual-the four factors that are involved in a weighted nonlinear least-squares fitting. The resulting potential is able to yield good agreement with the structure and energetics of Mo molecules, two-dimensional Mo structures, three-dimensional Mo crystals, small S molecules, and binary Mo-S crystal structures. We illustrate the capabilities of the new potential by presenting results of the simulation of friction between MoS2 layers. The results are consistent with our previous static potential surface calculations using density-functional theory.