Hot electrons and the approach to metallic behaviour in K-x(KCl)(1-x)

The approach to the metallic phase of molten K-x(KCl)(1-x) mixtures is studied using ab initio molecular dynamics based on finite-temperature density functional theory. The finite electronic temperature is found to result in new and unexpected effects. In particular, we observe a thermally induced lowering of the predicted DC conductivity, which greatly improves the agreement with the experiment, and a widening of the HOMO-LUMO energy gap. We expect that these are genuinely new physical effects which could be observed also in other systems.