Infinite-order transitions in density-functional models of wetting.

A class of density-functional models for wetting transitions is defined. A necessary condition for the transitions to be of higher than first order is derived. A locus of wetting transitions in the plane of two model field variables is determined on which there are states of first-order and of higher-order, including infinite-order, transitions. The observed behavior is rationalized via a different but related, analytically soluble model.