Electronic states in metal-ammonia solutions

Quantum simulation studies have been performed on metal-ammonia solutions for a wide range of concentrations using a model consisting of excess electrons in a molecular solvent. At low electron concentrations, the electron density is localized, and the electrons pair to form peanut-shaped bipolarons. At higher electron concentrations, the bipolarons exhibit a tendency to cluster. Eventually, at yet higher concentrations, the electron density becomes delocalized and spans the system indicating that the system has become metallic.