Determining temperature-pressure-density relations of shock-compressed post-transition metals using optimal functionals

Dynamic compression techniques offer very useful ways of measuring the equation of state (EOS) of materials at extreme conditions. Many properties, in particular the pressure-density relation along the shock Hugoniot curve, can usually be determined with high accuracy. However, there lacks a generic way to measure temperature. This is problematic when studying phase transformation boundaries of non-transparent materials, which can have large uncertainties depending on the EOS model being used. We propose a method for determining the temperature-pressure-density relation of materials under shock compression using quantum simulations based on optimal functionals. The choice of the functional is constrained by well-established experimental data, such as pressure-density Hugoniot and static compression results. These constraints are from multiple regions of the phase space, therefore making our predictions widely reliable. We apply this method to studying post-transition metals, of which the phase and structural property changes are of great interest to the high-pressure and materials physics communities.

Work prepared under the auspices of LLNL under contract DE-AC52-07NA27344.