A DENSITY-FUNCTIONAL STUDY OF THE EFFECTS OF AN EXTERNAL ELECTRIC-FIELD ON ADMOLECULE-SURFACE SYSTEMS

The influence of an external electric field of a magnitude typical of those in STM current-induced excitation experiments on the admolecule- surface and intramolecular bonds of OH, BeH and NO adsorbed on Si(111) and BW on C(111) is investigated using ab initio density functional c luster techniques. These systems represent four distinct adsorbate-sur face electronic polarization configurations. The bonding parameters ar e calculated as a function of the strength and direction of the electr ic field. The field-induced changes in the characteristics of both the admolecule-surface and the intramolecular bonds show strong dependenc e on their polarization configuration. (C) 1998 Elsevier Science B.V. All rights reserved.