Although the attractive van der Waals interaction between individual molecules varies as R-6, the interaction of a molecule with a nearby solid (a homogeneous collection of molecules) varies as R-3, where R is its vertical distance above the surface. Confirm this assertion. Calculate the interaction energy between an Ar atom and the surface of solid argon on the basis of a Lennard-Jones (6, 12)-potential. Estimate the equilibrium distance of an atom above the surface.