Understanding the theoretical properties of materials in the warm dense matter (WDM) and dense plasma regimes is a central goal in the development of key energy technologies, such as advanced nuclear reactors and inertial confined fusion, shock physics, plasma science, and stockpile stewardship. The project has developed an innovative new technique to simulate dense plasmas of second-row material elements for the first time. The project will use the Blue Waters leadership system to apply this new technique to a number of key materials in order to provide guidance to shock wave experiments and establish benchmarks for other theoretical approaches. The project proposes to simulate a set of materials on a grid of temperature-density points in order to derive the equation of state (EOS) under plasma conditions and in the regime of WDM. Results from this project will be of immeasurable importance to the designers at the National Ignition Facility (NIF) and at other high-energy-density-physics facilities. Students will be extensively involved with the project, which advances the NSF mission to support basic research that may contribute to the nation?s prosperity.
To study the WDM regime, the project will combine a novel PIMC simulations with standard, Kohn-Sham density functional molecular dynamics (KS-DFMD) simulations, which are more efficient at lower temperatures. While KS-DFMD has been used to accurately predict the structure of many solids and liquids up to temperatures on the order of 100,000 K, it is not applicable at much higher temperatures because the number of partially occupied electronic orbitals reaches intractably large numbers. The alternate method, orbital-free density functional molecular dynamics (OF-DFMD) yields inaccurate EOS results because no existing free energy functional has been developed. Collaborators at Department of Energy (DOE) national labs will use the PIMC EOS data both as comparisons to existing semi-empirical, EOS-generating schemes, and as inputs for continuum radiation hydrodynamics simulations. The project aims to establish an efficient pipeline from PIMC to macroscopic continuum studies of materials response. An emphasis will be placed on benchmarking such methods for plasmas of heavy elements at very high temperatures (~100 eV) and low densities that are generated when Hohlraum radiation heats the ablator material in indirect drive laser experiments.
