Intermolecular and Surface Forces, 3rd Edition

6 Van der Waals Forces

6.1 Origin of the Van der Waals-dispersion Force between Neutral Molecules: the London Equation

The various types of physical forces described so far are fairly easy to understand, since they arise from straightforward electrostatic interactions involving charged or dipolar molecules. But there is a another type of force that like the gravitational force—acts between all atoms and molecules, even totally neutral ones such as helium, carbon dioxide, and hydrocarbons. These forces have been variously known as dispersion forces, London forces, charge-fluctuation forces, electrodynamic forces, and induced-dipole-induced-dipole forces. We shall refer to them as dispersion forces, since it is by this name that they are most ...