Modes of counterion density fluctuations and counterion-mediated attractions between like-charged fluid membranes - art. no. 031507

Counterion-mediated attractions between like-charged fluid membranes are lo ng ranged and nonpairwise additive at high temperatures. At low temperature s, however. they are pairwise additive, and decay exponentially with the me mbrane separation. Using a simple model for the electrostatic attraction be tween like-charged surfaces, we show that the nature of these attractions i s determined by the dominant modes of fluctuations in the density of counte rions. While the nonpairwise additive interactions arise from long-waveleng th fluctuations and vanish at zero temperature, the short-ranged pairwise a dditive interactions arise from short-wavelength fluctuations and are stron ger at low temperatures.