Modeling the elastic properties of bcc iron in Earth’s core by quantum statistical physics

Abstract

Recently, the emergence of bcc iron has opened a promising direction for exploring Earth’s deepest regions. However, the high mobility of iron atoms in the bcc phase has constituted many impediments to research projects on mechanical behaviors under extreme conditions. This article presents how to improve the predicament via the fundamental tools of quantum mechanics. Specifically, we leverage available first-principle data to construct a new extended Rydberg potential for iron. This potential can accurately describe the equation of state of bcc iron up to at least 450 GPa and 7700 K. Then, we develop the statistical moment method to infer elastic properties from Rydberg parameters. This approach enables us to fully evaluate compressive and vibrational effects on the mechanical deformation of bcc iron without complicated computational procedures. Our calculations show a quantitative agreement with the latest first-principle simulations. Hence, they would be advantageous for explaining seismic observations on Earth-core elasticity.