Fluctuations and ordering in macroion suspensions

We calculate the static properties of macroion density fluctuations in both bulk and in confined, strongly interacting, macroion suspensions (macroions interact via the Derjaguin-Landau-Verwey-Overbeek potential) in terms of a simple density-functional ansatz. We show how to map a strongly interacting suspension to a weakly interacting one and obtain the renormalized charge, diameter and scattering structure factors analytically. The model is extrapolated to predict crystalline order in terms of a Hansen-Verlet-type of criterion as well as an effective hard-sphere crystallization condition, and good agreement with simulations is found. The increase in correlations observed in recent experiments in two, confined layers is demonstrated.