  We demonstrate the practical feasibility of calculating transport
coefficients such as the viscosity of liquids completely from first principles
using the Green-Kubo relations. Results presented for liquid aluminum are shown
to have a statistical error of only ca. 5%. The importance of such calculations
is illustrated by results for a liquid iron-sulfur alloy under Earth's core
conditions, which indicate that the viscosity of the liquid outer core is not
substantially higher than that of typical liquid metals under ambient
conditions.
