SCREENING AND ASYMPTOTIC DECAY OF PAIR DISTRIBUTIONS IN ASYMMETRIC ELECTROLYTES

An accurate description of the screening behavior of asymmetric binary electrolyte solutions is obtained by applying the dressed ion theory to acquire the three leading terms in the asymptotic decay of the radi al pair distribution function g(ij)(r) at large distances r. These ter ms give a surprisingly good representation of the distribution functio n for quite small r values. A minimum of two asymptotic terms are need ed for representing g(ij)(r) at moderately large r in a quite wide con centration range. The relationships between the large r asymptotic beh avior of charge-charge, density-density, and charge-density correlatio ns are investigated by means of the dressed ion distribution functions . The role that the dielectric response function of the electrolyte pl ays for the asymptotic behavior is illuminated and the relationship be tween this function and the dressed ion charge distributions is given. Ionic effective charges, effective permittivities, and decay lengths and their higher order analogues are calculated for 1:2 electrolytes u sing the hypernetted chain approximation. (C) 1998 American Institute of Physics. [S0021-9606(98)51044-6].