Computer simulation of dissociative equilibrium in aqueous NaCl electrolyte with account for polarization and ion recharging. Model of interactions

Abstract

Comparative analysis of different models applied in theoretical studies of electrolytes points to the considerable role of polarization interactions. In order to study aqueous electrolytes on the molecular level, a detailed model is presented of intermolecular interactions that accounts in explicit form, apart from Coulombic, exchange, and dispersion interactions, also many-body interactions caused by polarization of solvent molecules in the field of ions and ion polarization in the field of solvent molecules, and also many-body covalent interactions, effects of excess charge transfer and effects of partial counterion recharging. Numeric values of parameters for an aqueous NaCl solution are obtained by correlation of the calculated values of free energies and entropy of the first reactions of vapor molecule addition to hydrate ion shells with the corresponding experimental values and also from the experimental data on the dissociation energy and IR vibration frequencies of the ion pair and quantum-chemical calculation of the energy of stable configurations of a hydrated ion pair. A special form of describing many-body interactions allows by more than an order of magnitudes reducing the extent of the required calculations and makes it possible to apply the developed model for computer simulation of aqueous electrolytes at the room temperatures.