DIVERGENCE OF THE POINT TENSION AT WETTING

To determine the behavior of the line-point tension tau at the wetting transition, we consider a two-dimensional Ising model with appropriate boundary conditions and investigate suitable definitions of tau associated with the junction of an interface tilted with average angle theta(c) and another lying along the substrate. Size-dependent fluctuations in the point of contact require that tau be defined through a convolution sum. Hence tau almost-equal-to ln(1/theta(c)) as theta(c) --> 0 (wetting transition), which can be understood as a consequence of the entropic repulsion of the tilted part of the interface against the substrate.