Ab initio equation of state of iron up to 1500 GPa

Using ab initio molecular dynamics simulations, we calculate the equation of state of iron in the solid phase for both the hcp and bcc structures as well as the high-pressure melting curve up to 15 Mbars. We first find that the melting temperature increases up to 11 000 K at the highest pressures investigated following a semiempirical melting law over the entire pressure domain. We also investigate the stability of the bcc phase of iron beyond Earth's core conditions (3 Mbars) and find that the temperature at which the bcc phase is mechanically stabilized increases with density. Finally, we provide simple fits of these results for convenient use in the modeling of Earth-like exoplanets up to ten Earth masses, which requires accurate knowledge of the properties of iron up to 15 Mbars. DOI: 10.1103/PhysRevB.87.094102