CORRELATIONS BETWEEN MACROIONS IN MIXTURES OF CHARGED AND UNCHARGED MACROPARTICLES

Addition of uncharged or charged macroparticles to a solution of macro ions and counterions significantly affects the macroion-macroion corre lation function. This effect is studied using the hypernetted-chain in tegral equation. Two simple models are examined: (i) a multicomponent primitive model treats a solution as a mixture of charged and uncharge d hard spheres, (ii) a one-component model where the electrostatic int eractions are accounted for by the screened Coulomb potential and the effect of neutral macroparticles is given by an approximate ''volume e xclusion'' potential. Both models ignore the molecular nature of solve nt. The calculations presented here indicate that the one-component mo del is a poor representation of the actual interactions between macroi ons in the presence of the neutral macroparticles represented as hard spheres. In the second part of the work we study the mixtures of macro ions (two positively charged macroions that differ in size) with a com mon counterion. The radial distribution functions are presented for sy stems containing mono- or divalent counterions for a range of macroion concentrations.