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)