  Liquid NaSn alloys in five different compositions (20, 40, 50, 57 and 80%
sodium) are studied using density functional calculations combined with
molecular dynamics(Car-Parrinello method). The frequency-dependent electric
conductivities for the systems are calculated by means of the Kubo-Greenwood
formula.
  The extrapolated DC conductivities are in good agreement with the
experimental data and reproduce the strong variation with the concentration.
The maximum of conductivity is obtained, in agreement with experiment, near the
equimolar composition.
  The strong variation of conductivity, ranging from almost semiconducting up
to metallic behaviour, can be understood by an analysis of the
densities-of-states.
