GINZBURG CRITERION FOR COULOMBIC CRITICALITY

To understand the range of close-to-classical critical behavior seen i n various electrolytes, generalized Debye-Huckel theories (that yield density correlation functions) are applied to the restricted primitive model of equisized hard spheres. The results yield a Landau-Ginzburg free-energy functional for which the Ginzburg criterion can be explici tly evaluated. The predicted scale of crossover from classical to Isin g character is found to be similar in magnitude to that derived for si mple fluids in comparable fashion. The consequences in relation to exp eriments are discussed briefly.