First-Principles Equation of State and Shock Hugoniot Calculations of Lithium Fluoride and Sodium

We perform path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter (WDM) states of lithium fluoride and sodium. While DFT-MD is sufficient at low temperatures (T<106 K), PIMC efficiently provides accurate results at higher temperatures using free-particle nodes for first-row elements and localized, Hartree-Fock nodes for second-row elements. PIMC and DFT-MD provide consistent pressures, internal energies, and pair-correltation functions in intermediate temperature ranges. Combined results provide a coherent equation of state across a wide density-temperature range (2-15 g/cc and 104-109 K). The pair-correlation functions and the electronic density of states reveal an evolving plasma structure and ionization process that is driven by temperature and density. Finally, the computed shock Hugoniot curves show maxima in compression as the first and second shells are ionized.