Lattice Thermal Conductivity of MgSiO<sub>3</sub> Perovskite and Post-Perovskite under Lower Mantle Conditions Calculated by Deep Potential Molecular Dynamics
Fenghu Yang, Qiyu Zeng, Bo Chen, Dongdong Kang, Shen Zhang, Jianhua Wu, Xiaoxiang Yu, Jiayu Dai
Abstract
Lattice thermal conductivity ( κ lat ) of MgSiO 3 perovskite and post-perovskite is an important parameter for the thermal dynamics in the Earth. Here, we develop a deep potential of density functional theory quality under entire thermodynamic conditions in the lower mantle, and calculate the κ lat by the Green–Kubo relation. Deep potential molecular dynamics captures full-order anharmonicity and considers ill-defined phonons in low- κ lat materials ignored in the phonon gas model. The κ lat shows negative temperature dependence and positive linear pressure dependence. Interestingly, the κ lat undergos an increase at the phase boundary from perovskite to post-perovskite. We demonstrate that, along the geotherm, the κ lat increases by 18.2% at the phase boundary. Our results would be helpful for evaluating Earth’s thermal dynamics and improving the Earth model.