Ab initio calculations of hcp and bcc Fe at extreme conditions
L. Koči, A. B. Belonoshko and R. Ahuja
The determination of the Fe phase stabilities at low pressures and temperatures is fairly uncontroversial from experiments and theoretical calculations. However, at extreme conditions, it is still a polemic subject. In this work, the properties of hexagonal close-packed and body-centered cubic Fe have been studied by means of ab initio molecular dynamics (AIMD) within the framework of density functional theory (DFT). For the hcp Fe, the calculations regarding the equation of state (EOS) agree well with both experiment and previous calculations. From stress tensor analysis, the bcc phase shows a deviation from the stability region at approximately P = 230 GPa, T = 2600 K.
Keywords: Fe, pressure, molecular dynamics, stress, bcc, hcp.