title: Numerical convergence of the self-diffusion coefficient and viscosity obtained with Thomas-Fermi-Dirac molecular dynamics.
abstract: Computations of the self-diffusion coefficient and viscosity in warm dense matter are presented with an emphasis on obtaining numerical convergence and a careful evaluation of the standard deviation. The transport coefficients are computed with the Green-Kubo relation and orbital-free molecular dynamics at the Thomas-Fermi-Dirac level. The numerical parameters are varied until the Green-Kubo integral is equal to a constant in the t→+∞ limit; the transport coefficients are deduced from this constant and not by extrapolation of the Green-Kubo integral. The latter method, which gives rise to an unknown error, is tested for the computation of viscosity; it appears that it should be used with caution. In the large domain of coupling constant considered, both the self-diffusion coefficient and viscosity turn out to be well approximated by simple analytical laws using a single effective atomic number calculated in the average-atom model.
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: J-F
authors.initials: JF
authors.lastname: Danel
authors.forename: L
authors.initials: L
authors.lastname: Kazandjian
authors.forename: G
authors.initials: G
authors.lastname: Zérah
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004058:Diffusion; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D014783:Viscosity