Cratering due to surface defects in the Gaussian model

Surface defects on freshly applied liquid films like the phenomenon of cratering are characterized by almost discontinuous interfacial profiles. Our purpose is to model the effect of surface inhomogeneities and impurities that influence the equilibrium configuration of the surface film. We therefore employ the Gaussian model which is known to provide a simple equilibrium statistical thermodynamics description of the liquid–vapor interface. By modifying previous work by Weeks, we allow for additional external forces acting on the interface and discuss the resulting shape of the surface profile. Even local application of external forces leads to deviation from the plane surface decaying on a macroscopic length scale. This does not accurately model the cratering phenomenon. In systems, which can be described by our Gaussian model, surface tension forces will always lead to a smooth interfacial profile.