HIGHLY ASYMMETRIC ELECTROLYTE - TRIPLET CORRELATION-FUNCTIONS FROM SIMULATION IN ONE-COMPONENT AND 2-COMPONENT MODEL SYSTEMS

The colloid triplet correlation function of a two-component asymmetric (charge asymmetry 1:20) electrolyte has been investigated by means of molecular dynamics simulation. The departure from Kirkwood's superposition approximation is qualitatively the same as that found in hard-sphere and LJ model systems. The simpler one-component model with an effective pair potential underestimates the probability of finding triplets at small separations. In this region, the polarization of the small ions exerted by the triplets becomes nonadditive, that is, the polarization cannot be described as a sum of the polarization of three separate colloidal pairs. Thus, at these separations an effective pair potential can not fully describe the effective colloidal interaction.