Cluster variational method for a fluid in a narrow capillary

Abstract
We present a theoretical study of a fluid in a narrow planar capillary, including the effects of the periodic structure of the confining walls. A layering transition had been observed for the same model in a previous Monte Carlo simulation, but it is missing in our density-functional calculation. The transition is recovered with an approach based on the cluster variational method, which treats the free energy as a functional of the four-particle distribution function.