Density-functional account of van der Waals forces between parallel surfaces

The applicability of density-functional theory is extended to the area of van der Waals interactions between macroscopic bodies, in particular between two parallel surfaces. It is shown how the strength and the asymptotic form, including the van der Waals planes for the surfaces can be calculated with the electronic densities and the static image planes of the interacting objects as the only input. The calculation is carried out easily in a simple density-functional scheme, suggesting the possibility of extensions to the description of forces between more generally shaped macroscopic bodies, including the sample and tip in scanning-force microscopy. (C) 1998 Published by Elsevier Science Ltd.