Mass Transport Properties of LiD-U Mixtures from Orbital Free Molecular Dynamics Simulations and a Pressure-Matching Mixing Rule

Burakovsky, Leonid¹  Kress, Joel D.¹  Collins, Lee A.¹ 

[1] Los Alamos National Laboratory

关键词: Plasma Physics & Fusion Technology(70);    BENCHMARKS;    DIFFUSION;    ELECTRONS;    FUNCTIONALS;    MIXTURES;    PHASE SPACE;    SELF-DIFFUSION;    SHEAR;    TRANSPORT;    VISCOSITY;   

DOI  :  10.2172/1042987
RP-ID  :  LA-UR-12-21806
PID  :  OSTI ID: 1042987
Others  :  TRN: US1203068

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来源: SciTech Connect

【 摘 要 】

Mass transport properties for LiD-U mixtures were calculated using a pressure matching mixture rule for the mixing of LiD and of U properties simulated with Orbital Free Molecular Dynamics (OFMD). The mixing rule was checked against benchmark OFMD simulations for the fully interacting three-component (Li, D, U) system. To obtain transport coefficients for LiD-U mixtures of different (LiD){sub x}U{sub (1-x)} compositions as functions of temperature and mixture density is a tedious task. Quantum molecular dynamics (MD) simulations can be employed, as in the case LiD or U. However, due to the presence of the heavy constituent U, such simulations proceed so slowly that only a limited number of numerical data points in the (x, {rho}, T) phase space can be obtained. To finesse this difficulty, transport coefficients for a mixture can be obtained using a pressure-matching mixing rule discussed. For both LiD and U, the corresponding transport coefficients were obtained earlier from quantum molecular dynamics simulations. In these simulations, the quantum behavior of the electrons was represented using an orbital free (OF) version of density functional theory, and ions were advanced in time using classical molecular dynamics. The total pressure of the system, P = nk{sub B}T/V + P{sub e}, is the sum of the ideal gas pressure of the ions plus the electron pressure. The mass self-diffusion coefficient for species {alpha}, D{sub {alpha}}, the mutual diffusion coefficient for species {alpha} and {beta}, D{alpha}{beta}, and the shear viscosity, {eta}, are computed from the appropriate autocorrelation function. The details of similar QMD calculations on LiH are described in Ref. [1] for 0.5 eV < T < 3 eV, and in Ref. [2] for 2 eV < T < 6 eV.