Equation of State of Warm Condensed Matter

ABSTRACTRecent advances in computational condensed matter theory have yielded accurate calculations of properties of materials. These calculations have, for the most part, focused on the low temperature (T=0) limit. An accurate determination of the equation of state (EOS) at finite temperature also requires knowledge of the behavior of the electron and ion thermal pressure as a function of T. Current approaches often interpolate between calculated T=0 results and approximations valid in the high T limit. Plasma physics-based approaches are accurate in the high temperature limit, but lose accuracy below T∼Tfermi. We seek to “connect up” these two regimes by using ab initio finite temperature methods (including linear-response[l] based phonon calculations) to derive an equation of state of condensed matter for T<Tfermi.We will present theoretical results for the principal Hugoniot of shocked materials, including carbon and aluminum, up to pressures P>100 GPa and temperatures T> 104K, and compare our results with available experimental data.