Double lattice potential for molecular dynamics simulation of silicon with demonstrated validity.

To reproduce the diamond structure of silicon, double lattice (DL) potential constructed from two interatomic potentials for face centered cubic (fcc) lattice, is proposed for molecular dynamics (MD) simulations. For the validity test of MD simulation, the Tersoff potential, the Stillinger and Weber (SW) potential, the environment-dependent interatomic (EDI) potential, the charge optimized many-body (COMB) potential, and the modified embedded-atom (MEAM) potential have been also employed for comparison. The crystal lattice of simulated silicon system is identified by calculating the distribution functions of the distances between the atoms and the angles between the lines linking an atom with its nearest neighbors. The results are also compared with the perfect silicon crystal. The crystal lattice, the crystallization temperature, and elastic constants have been calculated from MD simulations using above potentials. The results show that the systems with modified Tersoff, SW, EDI, COMB, and MEAM potentials could not exhibit the diamond structure and only the DL potential gives diamond lattice. The ground state for DL potential is the wurtzite structure, and the metastable state formed during rapid cooling is the cubic diamond structure. The physical parameters obtained from the simulation with DL potential are in agreement with the experiment results. This work indicated that only DL potential is valid for MD simulation of silicon crystal among above various potentials.