A Study On Ornstein-Zernike Equation Theory For Electrolytes Based On First-Order Mean Spherical Approximation

In the theoretical research of chemical engineering and materials science, the analytical expressions of radial distribution function and total correlation function of Ornstein-Zernike integral equation is very important. In this work, we establish and solve the equation for electrolytes in a simple, analytical and consistent manner to obtain the like and unlike correlation functions for charged fluids. We have:(1) The hard sphere and Coulombic potentials modeling are improved with the Yukawa potential, respectively. The corresponding correlations are the essentials to the hard spherical softness and the integral convergence of Coulombic potential.(2) The internal energy and Helmholtz free energy are modified with the entropy correction to ensure the correct results of contact values of radial distribution function.(3) Based on the improved direct correlation functions for hard sphere and Coulombic potentials modeling and some mathematical skills, a new method is established to solve the OZ integral equation analytically, in which the first-order mean spherical approximation is also incorporated. The combination of mathematical analysis technique and statistical mechanic theory to investigate the chemical properties is the main feature of this work.(4) The obtained parameters for the new added Yukawa potentials have the physical meaning, where the exponential terms refer to the screening strength of ions, and the coefficient terms refer to the deviating extent of original MSA within the contact area.(5) The radial distribution functions and total correlation functions of electrolyte solutions are calculated with a wide range of reduced densities and temperatures. The results are modified obviously when compared with those from the MSA. And the analytical process is simply and self-consistent compared with that by the GMSA.