Electrostatic correlations in electrolytes: Contribution of screening ion interactions to the excess chemical potential

A new theory for the electrostatic component of the chemical potential for homogeneous electrolytes modeled with the primitive model is developed. This Mean Countershell Approximation (MCSA) is an analytic theory derived by including the interactions between the ions' screening clouds. At molar concentrations, these contribute substantially to the excess chemical potential but are absent in classical Debye-Huckel and Mean Spherical Approximation (MSA) theories. Simulations show that the MCSA is highly accurate, including at the low dielectric constants of ionic liquids. While sharing a mathematical framework with the MSA, the MCSA has simpler formulas and is qualitatively more accurate when there is ion size asymmetry.

Automated summary

The new theory MCSA for the electrostatic component of the chemical potential in homogeneous electrolytes models interactions between ions' screening clouds, contributing substantially at molar concentrations and being accurate even in low dielectric constants. Different from Debye-Huckel and MSA theories, the MCSA has simpler formulas and is qualitatively more accurate, especially when there is ion size asymmetry.