Benchmarking phase transitions in periclase under multi-megabar pressures

Abstract:

Periclase (MgO) is a prototype rock-forming mineral in planets, a pressure calibrator in diamond-anvil cell experiments, and a window material in shock experiments. Therefore, it is essential to accurately constrain its phase transitions (B1-B2 and solid-liquid), equation of state (EOS), and physical properties at multi-megabar (Mbar) pressures. However, this has remained challenging for both theory and experiment [as an example, previous work (1,2,3) report B1-B2 transition pressures that vary by ~20%]. In this presentation, we show our latest research on MgO from first-principles calculations. Our calculations are based on density functional theory using an optimal exchange-correlation functional, which is jointly constrained by static experiments, shock experiments, and many-body quantum Monte Carlo calculations (4,5), as well as quantum molecular dynamics, which enables a complete account of anharmonic effects at high temperatures (6), thereby providing an accurate theoretical benchmark for the phase transitions in MgO. These results provide important mineral physical inputs that are useful for studies in earth and planetary sciences and high-pressure physics.

This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856, the University of Rochester, and the New York State Energy Research and Development Authority. The support of DOE does not constitute an endorsement by DOE of the views expressed in this abstract.

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4. S. Zhang et al., Bull. Am. Phys. Soc. 64, BAPS.2019.MAR.P17.00003 (2019).
5. S. Zhang, F. Malone, and M. A. Morales, Bull. Am. Phys. Soc. 65, BAPS.2020.MAR.M03.00002 (2020).
6. R. Paul, S. X. Hu, and V. V. Karasiev, Phys. Rev. Lett. 122, 125701 (2019).