First-principles thermal equation of state and thermoelasticity of hcp Fe at high pressures

TL;DR

This paper uses first-principles calculations to analyze the thermodynamic and elastic properties of hcp iron at high pressures and temperatures, providing insights relevant to geophysics and materials science.

Contribution

It presents a comprehensive first-principles approach to determine the thermal equation of state and thermoelasticity of hcp iron, including electronic and vibrational effects, at high pressures and temperatures.

Findings

Calculated elastic moduli and equation of state properties as functions of temperature and pressure.

Provided detailed comparison with experimental measurements and theoretical predictions.

Analyzed behavior of bulk modulus, thermal expansion, and Gruneisen ratio under extreme conditions.

Abstract

We investigate the equation of state and elastic properties of hcp iron at high pressures and high temperatures using first principles linear response linear-muffin-tin-orbital method in the generalized-gradient approximation. We calculate the Helmholtz free energy as a function of volume, temperature, and volume-conserving strains, including the electronic excitation contributions from band structures and lattice vibrational contributions from quasi-harmonic lattice dynamics. We perform detailed investigations on the behavior of elastic moduli and equation of state properties as functions of temperature and pressure, including the pressure-volume equation of state, bulk modulus, the thermal expansion coefficient, the Gruneisen ratio, and the shock Hugoniot. Detailed comparison has been made with available experimental measurements and theoretical predictions.