NONMETAL-METAL TRANSITION IN METAL-MOLTEN-SALT SOLUTIONS

The method of ab initio molecular dynamics, based on finite-temperatur e density-functional theory, is used to study the nonmetal-metal trans ition in two different metal-molten-salt solutions, K-x(KCl)(1-x) and Na(NaBr)(1-x). As the excess metal concentration is increased the elec tronic density becomes delocalized and percolating conducting paths ar e formed, making a significant dc electrical conductivity possible. Th is marks the onset of metallic regime. By calculating several electron ic and structural properties, remarkable differences between the two s olutions are observed. The anomalous behavior of Na(NaBr)(1-x), typica l of all the Na-NaY solutions, is found to be related to the strong at tractive interaction between the sodium ions and the excess electrons.