Simulation of Electrons in Molten Salts

Metal molten salt solutions exhibit a number of interesting properties with variation of the metal concentration. In the dilute limit, the metal valence electrons are released to form F-center-like localized states. At higher concentrations, metallic behavior sets in.

A theoretical approach to the properties of these systems obviously requires a correct quantum-mechanical treatment of the solvated electrons. We show here that an approach that uses a local spin density description of many electron interactions, is a powerful and efficient method for the study of the adiabatic dynamics of such systems.

We apply our approach to the case of one and two solvated electrons. In the first case we confirm the F-center model and elucidate the mechanism of electron diffusion. In the case of two solvated electrons, we find that parallel spin electrons repel each other and form separate F-center-like states. Antiparallel spin electrons, instead, attract each other and coalesce into a single bipolaronic complex. The diffusion of the bipolaron, while bound, occurs on a ionic time scale. However, dissociation process occur during which the electrons can acquire a high mobility leading to a large electronic diffusion.

At even higher concentrations preliminary indication of clustering and of metallic behavior are observed.