ABSTRACT
This chapter deals with the physical interactions between discrete atoms or molecules. Physical interactions are those that do not result in the formation or breaking of chemical bonds. In this model, electrons remain in the vicinity of their own molecular particle (atom or molecule), rather than being more widely dispersed. The interactions between molecular particles (attractive or repulsive depending on circumstances) chemists and physicists call ‘van der Waals interactions’ after the nineteenth-century physicist Johannes van der Waals. There is the choice between ‘atomistic’ or particle mechanics and ‘continuum’ mechanics depending on the circumstances. The latter is far more effective and appropriate for engineering problems and the former is necessary for simulation of materials at the molecular level. Computer simulation uses both techniques. The properties of microclusters are especially appropriate for computer calculation because of the limited number of atoms involved.
