Application of molecular dynamics computations to the conformal ionic solution theory: Thermodynamics of binary molten salt mixtures

Abstract

An evaluation of the coefficient a (T,V) as defined in the equation for the excess Helmholtz free energy of mixing of binary solutions, ΔA_m^E=a (T,V)(λ_i−λ_j)²X_iX_j +..., derived from the conformal ionic solution theory is presented. This coefficient is shown to be negative and proportional to a fluctuation energy. The sign agrees with experimental calorimetric data of binary molten salt mixtures. A molecular dynamics computation of a (T,V) was made to compare theory and experiments. The calculated values are strongly dependent on the form of the repulsive contribution to the pair potentials (Tosi and Fumi model and Michielsen, Woerlee, Graaf, and Ketelaar model). Criteria for testing the repulsive part of proposed pair potentials are suggested as a result of this investigation.