Mass Transport in the Warm, Dense Matter and High-Energy Density Regimes

Joel Kress
Los Alamos National Laboratory

Large-scale hydrodynamical simulations of fluids and plasmas under extreme conditions require knowledge of certain microscopic properties such as diffusion and viscosity in addition to the equation-of-state. To determine these dynamical properties, we employ quantum molecular dynamical (MD) simulations on large samples of atoms. The quantum electrons are treated utilizing two forms of density functional theory (DFT): (1) Kohn-Sham (KS), and (2) orbital-free (OF). KS DFT is computationally intense due to its reliance on an orbital representation. The Thomas-Fermi approximation in OF DFT provides an efficient and systematic means for extending the quantum simulations to very hot conditions. We have performed KS and OF equilibrium MD calculations of the self-diffusion, mutual diffusion and shear viscosity for Al, Li, H, and LiH. We examine trends in these quantities and compare to more approximate forms such as the one-component plasma model. In a study inspired by the fuel/ablator interface in an inertial confinement fusion (ICF) target capsule, we have also performed non-equilibrium OFMD simulations of diffusion at the interface between a deuterium/tritium and carbon plasma.

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