A new generalization of the sullivan model for wetting transitions

Abstract

A new generalization of the Sullivan model for the wetting transition is constructed. To the exponential wall potential of the Sullivan model is added a square well of arbitrary depth and range. Although explicit solutions cannot be given, the different possible types of density profiles are systematically classified. It is argued that for shallow wells of long range, the wetting transition is of first order. Shallow wells of short range give continuous transitions, and the shift from the Sullivan case is calculated explicitly. A simplified version of the model allows a more quantitative criterion for a first-order transition to be formulated. It also points to the possibility that a continuous wetting transition is preceded by a first-order transition between two distinct, partially wet, states.