title: Quantum molecular dynamics simulations of transport properties in liquid and dense-plasma plutonium.
abstract: We have calculated the viscosity and self-diffusion coefficients of plutonium in the liquid phase using quantum molecular dynamics (QMD) and in the dense-plasma phase using orbital-free molecular dynamics (OFMD), as well as in the intermediate warm dense matter regime with both methods. Our liquid metal results for viscosity are about 40% lower than measured experimentally, whereas a previous calculation using an empirical interatomic potential (modified embedded-atom method) obtained results 3-4 times larger than the experiment. The QMD and OFMD results agree well at the intermediate temperatures. The calculations in the dense-plasma regime for temperatures from 50 to 5000 eV and densities about 1-5 times ambient are compared with the one-component plasma (OCP) model, using effective charges given by the average-atom code INFERNO. The INFERNO-OCP model results agree with the OFMD to within about a factor of 2, except for the viscosity at temperatures less than about 100 eV, where the disagreement is greater. A Stokes-Einstein relationship of the viscosities and diffusion coefficients is found to hold fairly well separately in both the liquid and dense-plasma regimes.
authors.affiliation: Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Kress
authors.forename: James S
authors.initials: JS
authors.lastname: Cohen
authors.forename: D P
authors.initials: DP
authors.lastname: Kilcrease
authors.forename: D A
authors.initials: DA
authors.lastname: Horner
authors.forename: L A
authors.initials: LA
authors.lastname: Collins