Structure and Dynamics of Liquid Iron under Earth's Core Conditions

TL;DR

This study uses first-principles molecular dynamics to investigate the structure and dynamics of liquid iron under Earth's core conditions, providing insights into its properties relevant to geophysics.

Contribution

The paper presents detailed first-principles simulations of liquid iron at core conditions, including structural and dynamical properties, with careful analysis of technical errors and validation against experimental data.

Findings

Liquid iron is a close-packed simple liquid under core conditions.

Diffusion coefficient and viscosity are similar to those of simple liquids at ambient conditions.

Results support the accuracy of first-principles methods for extreme conditions.

Abstract

First-principles molecular dynamics simulations based on density-functional theory and the projector augmented wave (PAW) technique have been used to study the structural and dynamical properties of liquid iron under Earth's core conditions. As evidence for the accuracy of the techniques, we present PAW results for a range of solid-state properties of low- and high-pressure iron, and compare them with experimental values and the results of other first-principles calculations. In the liquid-state simulations, we address particular effort to the study of finite-size effects, Brillouin-zone sampling and other sources of technical error. Results for the radial distribution function, the diffusion coefficient and the shear viscosity are presented for a wide range of thermodynamic states relevant to the Earth's core. Throughout this range, liquid iron is a close-packed simple liquid with a diffusion coefficient and viscosity similar to those of typical simple liquids under ambient conditions.