LATERAL SURFACE STARK-EFFECT IN CHEMISORBED MOLECULES

The influence of localized surface fields arising from local surface potential differences near structural and chemical surface irregularities on chemisorbed molecules is simulated by ab initio SCF-LCAO cluster calculations with a linear CO-Al cluster in the presence of an external point charge. Our exploratory study substantiates the notion of a local surface Stark effect induced shifting and splitting of the CO 2π*-type orbitals, which suggests an increased charge backdonation effect and, hence, an increased CO dissociation probability near surface defects, in accord with corresponding experimental observations. © 1990 Pergamon Press plc.