First-principles molecular-dynamics equation of state of liquid to dense plasma iron.

Abstract

We computed the equation of state of iron using extended first-principles molecular dynamics simulations, ranging from 7.874g/cm^{3} and 5500 K up to 47.2g/cm^{3} and 10^{9}K. We compared the principal Hugoniot curve with semiempirical models, average atom-based model predictions, and shock experiment results. We derived the Helmholtz free energy and the entropy via thermodynamic integration along isochores. We explore the ionization processes at play along the Hugoniot curve by analyzing the evolution of the electronic densities of states in the gigabar regime.