Development of a bond-order potential that can reproduce the elastic constants and melting point of silicon

Abstract

The Tersoff potential is one of the most widely used interatomic potentials for silicon. However, its poor description of the elastic constants and melting point of diamond silicon is well known. In this research, a new bond-order type interatomic potential has been developed that can reproduce the elastic constants and melting point of diamond silicon as well as the cohesive energies and equilibrium bond lengths of polytypes of silicon. We improved the original Tersoff potential function through the introduction of a flexible angular dependent term. In order to increase the robustness of the potential, systems that include a wide range of local atomic environments are employed for fitting. Optimized potential parameters were found using a genetic algorithm. The elastic constants and melting point of diamond silicon calculated using the developed potential turned out to be C 11 = 166.4GPa, C 12 = 65.3GPa, C 44 = 77.1GPa and T m = 1681K. It was also found that only elastic constants can be reproduced using the original Tersoff potential function, and that our proposed angular dependent term is a key to reproducing the melting point.