ON DIFFERENT TYPES OF DIPOLE-DIPOLE INTERACTION

This paper offers comments on some recent theoretical work, and more generally on the origin of field adsorption. It is suggested that neglect of atomic structure in recent calculations has led to invalid conclusions, and that some criticisms of the array model are misplaced. The results of an approximate classical model for field enhancement above a protruding atom are presented, as part of a comparison between theory and experiment. It is suggested that the neon "hopping bright spot" phenomenon could be a better flag bearer for exchange-integral effects , provided that cluster calculations can predict the apex location of adsorption. Possibly both exchange-integral and polarisation terms contribute to observed effects.