The effects of the physical cluster formation on pair-correlation functions for an ionic fluid.

A system of two integral equations, which is equivalent to the Ornstein-Zernike equation, results in two kinds of correlation functions which describe the apparent effects of the physical cluster formation on pair-correlation functions. Each pair-correlation function is equivalent to the sum of the two kinds of correlation functions, and the development of physical clusters, which are formed in an ionic fluid owing to the attractive Coulomb force between positive and negative charged particles, allows the dependence of the sum on the distance r between particular pair particles to develop the deviation from the behavior characterized as r-1. Then, their development makes the dependence of the sum on r have a tendency to approach the behavior characterized as r-3/2, and the two kinds of correlation functions aid in describing fractal structures of nonuniform particle distributions in ionic fluids.