Chemical potential of model electrolyte solutions consisting of hard sphere ions and hard dipoles from molecular simulations

Abstract

Mixtures of charged and dipolar hard spheres are important models for electrolyte solutions, in particular for developing molecular-based fluid theories. This study presents data for the ionic chemical potential from Monte Carlo simulations for mixtures where charged and dipolar hard spheres have the same diameter. Earlier simulation studies of this model focus on Helmholtz energy and internal energy. The chemical potential is a sensitive quantity for assessing and refining fluid theories and it is the determining quantity for calculating phase equilibria. We provide chemical potentials for different dipole moments, ionic charges, ion concentrations, and liquid-like densities. The data is obtained by two methods, a multistage sampling scheme as well as expanded ensemble transition matrix method. A system size study shows that standard Ewald summation is a valid method for calculating the chemical potential from molecular simulations and we ensure that finite size effects are negligible for the presented data.