The general theory of van der Waals forces

Publisher Summary The van der Waals forces refer to the attractive forces acting between any two neutral atoms or molecules that are separated by distance large compared to their own dimensions. These forces are of a long-range nature, which decrease with distance according to a power law. The basic idea of the theory is that the interaction between the bodies is considered to take place through a fluctuating electromagnetic field. This field is always present in the interior of a material medium and it also extends beyond its boundaries because of the thermodynamic fluctuations. Any change in the electrical proper ties of the medium in a certain region will, by Maxwell's equations, lead to a change in the fluctuation field that extends beyond that region. Therefore, the part of the free energy that is related to electromagnetic fluctuations is not determined by the properties of the substance solely at the point considered.