Individual activity coefficients of a solvent primitive model electrolyte calculated from the inverse grand-canonical Monte Carlo simulation and MSA theory

摘要

The recently developed inverse grand-canonical Monte Carlo technique (IGCMC) (S. Lamperski. Molecular Simulation 33, 1193 (2007)) and the MSA theory are applied to calculate the individual activity coefficients of ions and solvent for a solvent primitive model (SPM) electrolyte. In the SPM electrolyte model the anions, cations and solvent molecules are represented by hard spheres immersed in a dielectric continuum whose permittivity is equal to that of the solvent. The ions have a point electric charge embedded at the centre. A simple 1:1 aqueous electrolyte is considered. The ions are hydrated while the water molecules form clusters modelled by hard spheres of diameter d_s. The diameter d_s depends on the dissolved salt and is determined by fitting the mean activity coefficient ln γ_± calculated from IGCMC and from the MSA to the experimental data. A linear correlation is observed between d_s and the Marcus parameter ΔGHB, which describes the ion influence on the water association.