First-Principles Simulations and Shock-Hugoniot Calculations of Warm Dense Neon

Abstract:

All-electron path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) simulations provide a consistent, first-principles investigation of warm, dense neon plasmas in the density-temperature range of 1–15 g/cm³ and 10⁴–10⁸ K. At high temperatures, DFT-MD becomes intractable because of too many partially occupied bands, while at lower temperatures, PIMC is intractable because of approximations to fermion nodes. In combination, PIMC and DFT-MD pressures and internal energies provide a coherent equation of state with a region of overlap in which the two methods cross-validate each other. Pair-correlation functions at various temperatures and densities provide details of the plasma structure and the temperature-driven ionization process. The electronic density of states of neon shows that a gap persists for the highest density-temperature conditions studied here with DFT-MD. Finally, the computed shock Hugoniot curves show an increase in compression as the first and second shells are ionized. Funding provided by the NSF (DE-SC0010517). Computational resources provided by the National Center for Atmospheric Research.