Conductivity of liquid Al, Na, Pb and Mn calculated from first principles

Abstract

We calculated the conductivity of liquid Al, Na, Pb, and Mn, using the density-functional theory (the Siesta method with norm-conserving pseudopotentials and strictly confined basis functions) and the Kubo-Greenwood formalism. Supercells of up to 64 atoms were used for molecular dynamics simulations at a given temperature. After the equilibration, dielectric function and electron conductivity were evaluated at, and averaged over, a number of snapshot geometries. For all metals, good agreement with experimental results was obtained at simulation temperatures just beyond the melting point. The calculated variation of resistivity of Al, Na and Pb throughout ∼200 K above their respective melting points shows a qualitatively correct trend (a gradual increase of resistivity), with some quantitative deviations from the experiment. We attribute these deviations to the lowering of the liquid metal density with temperature, which effect was neglected in the present simulation. For Mn, we emphasize the importance of including spin polarization into the calculation, due to the presence of apparently stable local magnetic moments at the Mn atoms, which survive in liquid phase and exhibit antiferromagnetic-type correlations.