Improved First-Principles Equation-of-State Table of Deuterium for High-Energy-Density Science Applications

We present an improved first-principles equation-of-state (iFPEOS) table of deuterium covering densities 10^-3 < r < 1.6×10³ g/cm³ and temperatures 800 K < T < 256 MK. iFPEOS is based on the latest theoretical developments in quantum treatment of ions and electrons within the ab initio molecular dynamics driven by density-functional-theory approach. For an improved description of the electronic structure across temperature regimes, iFPEOS employs a meta-generalized-gradient-approximation free-energy exchange-correlation density functional with explicit temperature dependence. Nuclear quantum effects are taken into account via path-integral molecular dynamics. Comparing iFPEOS to other equation-of-state (EOS) models and latest experimental measurements we find that iFPEOS provides an improved agreement with experimental data for pressures up to 200 GPa and temperatures up to 60,000 K. For higher pressures and temperatures, however, iFPEOS predicts lower compressibility and higher sound speed along the Hugoniot, compared to experiment, thereby further confirming the systematic disagreement between theory and experiment in this regime.