Critical assessment of classical potentials for MgSiO3 perovskite with application to thermal conductivity calculations

Atomistic simulations using classical empirical potentials are an invaluable tool for studying minerals in lower-mantle conditions. Here we systematically survey literature potentials for MgSiO3 perovskite. The value of the present work is two-fold: (i) a systematic data set for a large number of potentials is determined, reproducing previous results where they exist and filling in gaps where they do not, and (ii) the first predictions using these potentials for the thermal-transport properties critical to geothermal models is provided. We focus particularly on the thermal expansion and the thermal-transport properties, both of which probe the anharmonic structure of the potential. Simple two-body potentials with the partially-ionic charges are found to be the most successful representation of MgSiO3 perovskite properties. The addition of a shell model or many-body interactions does not lead to any systematic improvement.

► Performance of the classical potentials for MgSiO3 perovskite properties is compared.
► Thermal conductivity is calculated using the best models for the first time.
► Stronger temperature dependence of the thermal conductivity is predicted than experimentally observed.
► Implications for the Earth’s mantle thermal conductivity are discussed.