A simple model for solutions of liquid alkali and alkali halides

Abstract

A simple model for metal-salt solutions is examined in the framework of hypernetted chain (HNC) theory. The proposed model hamiltonian retains only the essential features of the ion-ion interactions, while the gas of valence electrons is replaced by a uniform background. The calculated structure factors are in semi-quantitative agreement with existing neutron diffraction data for K-KCl and Rb-RbBr mixtures over the whole range of concentrations. In particular the theory reproduces the striking small angle scattering intensity observed in the experimental structure factors; this intensity is traced back to the surprisingly long range of the pair correlations. The decrease of entropy in going from the pure metal to the pure salt agrees with available thermodynamic measurements.