Insight of the thermal conductivity of ϵ-iron at Earth’s core conditions from the newly developed direct ab initio methodology

Abstract

The electronic thermal conductivity of iron at the Earth’s core conditions is an extremely important physical property in the geophysics field. However, the exact value of electronic thermal conductivity of iron under extreme pressure and temperature still remains poorly known both experimentally and theoretically. A few recent experimental studies measured the value of the electronic thermal conductivity directly and some theoretical works have predicted the electronic thermal conductivity of iron at the Earth’s core conditions based on the Kubo-Greenwood method. However, these results differ largely with each other. A very recent research has confirmed that for iron at the Earth’s core conditions, the strength of electron-electron scattering could be comparable to that for electron-phonon scattering, meaning that the electron-electron scattering should also be considered when evaluating the electronic thermal conductivity in the Earth’s core situations. Here, by utilizing a newly developed methodology based on direct non-equilibrium ab initio molecular dynamics simulation coupled with the concept of electrostatic potential oscillation, we predict the electronic thermal conductivity of iron in h.c.p. phase. Our methodology inherently includes the electron-phonon and electron-electron interactions under extreme conditions. Our results are comparable to the previous theoretical and experimental studies. More importantly, our methodology provides a new physical picture to describe the heat transfer process in ϵ-iron at the Earth’s core conditions from the electrostatic potential oscillation point of view and offers a new approach to study the thermal transport property of pure metals in the planet’s cores with different temperature and pressure.