Yukawa sticky m-point model of associating fluid

Abstract

The product-reactant Ornstein–Zernike approach, supplemented by the ideal network approximation, is formulated for the Yukawa sticky m-point (YSmP) model of associating fluid. The model is represented by the multicomponent mixture of the Yukawa hard spheres with m sticky points randomly located on the surface of each hard sphere. Extensions of the regular integral equation closures, which include polymer Percus–Yevick, polymer hypernetted chain and polymer mean spherical approximations, are presented. An analytical solution of the polymer mean spherical approximation is derived and closed form analytical expressions for the structure (contact value of the radial distribution function, structure factor) and thermodynamic (internal energy) properties of the YSmP model are obtained. Due to generality and flexibility of the model it can be used to study the properties of a number of different associating fluids, including water and aqueous solutions. By way of illustration liquid–gas phase diagrams for the model with m=0, 1, 2, 3, 4 are presented and discussed. Predictions of the theory for the liquid–gas phase diagram of the YS4P model with the parameters similar to those assumed in the frames of the statistical associating fluid theory to mimic water are in reasonably good agreement with the corresponding experimental data for water.