A molecular Debye-Hückel theory of solvation in polar fluids: An extension of the Born model

Abstract

A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of Debye-Hückel-like response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a Debye-Hückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated in a self-consistent way and can be used to evaluate the electrostatic contribution to the thermodynamic properties of a polar fluid. Our theory is applied to a dipolar hard sphere fluid as well as interaction site models of polar fluids such as water, where the electrostatic contribution to their thermodynamic properties can be obtained accurately.

Development of a Model for Electrostatic Contribution to the Osmotic Coefficient of Aqueous Electrolytes

“…However, few authors have tried to improve the D-H theory. Xian and Song 31,32 proposed a molecular D-H theory for electrolyte solution with size symmetry in which the dielectric response of an electrolyte solution is described by a linear combination of D-H-like response-modes to calculate the mean electric potential as well as the electrostatic contribution to thermodynamic properties.…”

“…However, few authors have tried to improve the D-H theory. Xian and Song , proposed a molecular D-H theory for electrolyte solution with size symmetry in which the dielectric response of an electrolyte solution is described by a linear combination of D-H-like response-modes to calculate the mean electric potential as well as the electrostatic contribution to thermodynamic properties. According to Xian and Song, the size asymmetry of an electrolyte solution yields a harge imbalanced border zone around a solute and the dielectric response to the solute is characterized by two types of charge sources, namely, a bare solute charge and a charge distribution due to size asymmetry.…”