Extension of van der Waals theory for supersaturated thin films.

The vapor/liquid interface properties play an essential role in both fundamental models and practical applications. Here, we describe a thin planar film surrounded by supersaturated vapor using the extension of van der Waals theory. We derive the analytical equilibrium conditions, which allow us to define the stress tensor and surface tension. Our model provides the surface tension dependence on the film thickness, correctly reflecting the vapor/liquid interface until full disappearance. The numerical estimations show that the surface tension crucially depends on the film thickness-a decrease in the thickness of 50% results in an 85% reduction in the surface tension.