\textit{Ab initio} lattice thermal conductivity of MgSiO${}_3$ across perovskite-postperovskite phase transition

Abstract

Lattice thermal conductivity (${\kappa }_{lat}$) of MgSiO${}_3$ postperovskite (MgPPv) under the Earth's lower mantle high pressure-temperature conditions is studied using the phonon quasiparticle approach by combing \textit{ab initio} molecular dynamics and lattice dynamics simulations. Phonon lifetimes are extracted from the phonon quasiparticle calculations, and the phonon group velocities are computed from the anharmonic phonon dispersions, which in principle capture full anharmonicity. It is found that throughout the lowermost mantle, including the D" region, ${\kappa }_{lat}$ of MgPPv is ~25% larger than that of MgSiO${}_3$ perovskite (MgPv), mainly due to MgPPv's higher phonon velocities. Such a difference in phonon velocities between the two phases originates in the MgPPv's relatively smaller primitive cell. Systematic results of temperature and pressure dependences of both MgPPv's and MgPv's ${\kappa }_{lat}$ are demonstrated.

References in corpus (8)

• Phonons and related properties of extended systems from density-functional perturbation theory
• Theoretical and experimental evidence for a post-perovskite phase of MgSiO3 in Earth's D" layer
• Unified theory of thermal transport in crystals and disordered solids
• Temperature dependent effective third order interatomic force constants from first principles
• Phonon Quasi-Particles and Anharmonic Free Energy in Complex Systems
• Thermal conductivity of MgO, MgSiO3 perovskite and post-perovskite in the Earth's deep mantle
• Pre-melting hcp to bcc Transition in Beryllium
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Cited by in corpus (4)

• Thermal conductivity of MgO in giant planetary interior conditions predicted by deep potential
• Anharmonic thermodynamic properties and phase boundary across the post-perovskite transition in MgSiO${}_3$
• Unique Hierarchical Rotational Dynamics Induces Ultralow Lattice Thermal Conductivity in Cyanide-bridged Framework Materials
• NaZnF3 as a low-pressure analogue of MgSiO3