A Combined Quantum Chemical Statistical Mechanical Simulation of the Hydration of Li⁺, Na⁺, F⁻, and Cl⁻

The hydration (or solvation) of the lithium, sodium, fluoride, and chloride ions are investigated using a combined quantum chemical statistical mechanical model. Radial distribution functions and the distribution of coordination numbers are reported and compared with other recent studies. An algorithm to investigate the geometry of the first solvation shell is proposed and applied to the four hydrated monatomic ions. The combined nature of the model enables an analysis of the coupling between the exchange repulsion and the induction energy. It is found that the coupling for the two cations is insignificant, while the two anions, especially the chloride ion, display a greater coupling between the exchange repulsion and the polarization. Induced dipoles and induction energies of the hydrated ions are also reported.