Minimum-modified Debye-Hückel theory for size-asymmetric electrolyte solutions with moderate concentrations

A minimum-modified Debye-Huckel (DH) theory for electrolytes with size asymmetry is developed. Compared with the conventional DH theory, the minimum-modified DH theory only introduces an extra surface charge density to capture the electrostatic effect of the size asymmetry of the electrolytes and hence facilitates a boundary element method for electrostatic potential calculation. This theory can distinguish the electrostatic energies and excess chemical potentials of ions with the same sizes but opposite charges, and is applied to a binary primitive electrolyte solution with moderate electrostatic coupling. Compared with the hyper-netted chain theory, the validity of this modified DH theory demonstrates significant improvement over the conventional DH theory.

Automated summary

A modified Debye-Huckel (DH) theory is developed to study electrolytes with size asymmetry. Compared to the conventional DH theory, the modified DH theory introduces an extra surface charge density to account for the electrostatic effect of size asymmetry and enables the use of a boundary element method for electrostatic potential calculation. This theory improves upon the conventional DH theory by distinguishing the electrostatic energies and excess chemical potentials of ions with the same sizes but opposite charges.