Effects of Dipole-Dipole Interaction on Multivalency of Adatoms: a Model of Valence Transition

Abstract

Effects of the dipole-dipole interaction on the multivalency of adatoms on the metal surfaces are studied. For the system with two adatoms, it is shown that the transition line exists, across which the valency of two adatoms in the ground state changes discontinuously. The result is extended to the system with many adatoms, and a model is proposed of the valence transition. The coverage dependence of the work function is also discussed.