Equation of state of Mg, MgO, and MgSiO3 at Mbar pressures

Abstract:

Understanding the processes that take place in planetary interiors largely depends on our knowledge of the equation of state of constituent materials. Properties of the liquid phase of minerals at high pressure is important to understand the structure and evolution of deep magma oceans, as well as guiding and interpreting high pressure experiments that reach the conditions inside planetary interiors. Using path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) simulations, we generate a consistent equation of state (EOS) for liquid Mg, MgO and MgSiO₃ [1,2] across a wide range of temperatures and pressures. We study their thermodynamic properties, characterize the atomic structure, and compare their electronic properties. We determine the onset of ionization of the inner electronic shells and relate the thermodynamic properties to the electronic structure. In order to guide future ramp and shock compression experiments, we derive the shock Hugoniot curve of each material, which are in obtaining good agreement with experiments. Finally, we apply linear mixing rules study non-ideal mixing effects.

References:

1. González-Cataldo, F., Soubiran, F., Peterson, H., & Militzer, B. Physical Review B 101 (2020): 024107.
2. Soubiran, F., González-Cataldo, F., Driver, K. P., Zhang, S., & Militzer, B. The Journal of Chemical Physics, 151 (2019): 214104.