Wide-range equations of state of carbon and boron materials from first principles*

Using several independent approaches (path integral Monte Carlo, density functional theory, and activity expansion), we performed extensive investigation providing the theoretical benchmark for the equations of state (EOS) of a series of low-Z materials (CHx, B, BN, and B4C) over a wide range of temperatures (0.1-1e4 eV) and densities (0.01-100 g/cc). Across the warm-dense regime, our predictions show remarkable consistency with experimental data and constrain the EOS to better than 4{\%}, with the largest uncertainties occurring at 1e6 K and 1 Gbar where K shell ionization occurs. Constrained by our first-principles data, we made improved EOS models to be used for the design and interpretation of high-energy-density and inertial confinement fusion experiments. We also discuss the strengths and weaknesses of empirical approaches such as the ideal-mixing approximation and the Arrhenius relation, as well as structural complexities during shock compression. (LLNL-ABS-780064)