Comparative investigations of the thermal expansivity of MgO at high temperature

Molecular dynamics simulations have been performed to investigate the thermal expansivity of MgO at high temperature using the very similar Lewis-Catlow and Stoneham-Sangster shell model potentials. In order to take account of non-central forces in crystals, the breathing shell model is also introduced in simulation. The volume thermal-expansion coefficient αP of MgO dependence of the temperature T at 0 and 135 GPa have been obtained and compared with the available experimental and theoretical results. Compared with shell model potentials, the molecular dynamics results obtained using breathing shell model potentials are more compressible. At an extended pressure and temperature ranges, αP has also been predicted.