Utilizing first principles calculations to map the equation of state of chromium: low temperature magnetic phases through warm dense matter

Chromium (Cr) is a critical elemental component in many engineering alloys, most notably the stainless steels. Recent experimental studies using static and shock compression have successfully mapped the Cr equation of state (EOS) through the melt curve and to high pressures exceeding 140 GPa. However, determining the EOS from the ultra-low temperature spin-density wave phases through the warm dense matter regime remains challenging. In this work, we employ advanced first principles calculations to extend the EOS table to temperature and pressure extremes. Low temperature phases and their pressure-induced magnetic transitions are determined with fully non-collinear density functional theory. The EOS of warm dense Cr above a temperature of 1 eV is determined with ab initio molecular dynamics and above 50 eV with all-electron average atom calculations. Simulation results and existing experimental data are finally used to constrain and optimize a Cr EOS table using the OpenSesame code.