Critical assessment of effective interfacial potentials based on a density functional theory for wetting phenomena on curved substrates

Abstract

In this Letter we examine an effective interfacial Hamiltonian approach for wetting phenomena based on two different density approximations in the framework of a density functional theory. The system under consideration is an attractive spherical wall subject to adsorption by a metastable liquid. We argue that, contrary to a planar geometry, in the spherical case the popular sharp-kink approximation leads to a considerable disagreement for the film thickness with numerical results obtained from density functional theory. We show that the deviation originates from the inaccuracy of the predicted liquid-gas surface tension. We further demonstrate that the prediction can be substantially improved when a soft-interface approximation is adopted, such that the liquid-gas interface is approximated by a smooth monotonic function.