THEORETICAL-STUDY OF CN CHEMISORBED ON THE PD(111) SURFACE

The chemisorption of CN on the Pd(111) surface has been studied by the DV-X-alpha and ASED-MO methods using cluster models. The binding energies and equilibrium geometries for several adsorption sites have been determined by the ASED-MO method. The results show that the center superposition site (hcp) with CN axis parallel to the surface and to the [112BAR] direction is the most stable site and the optimized height is equal to 1.51 angstrom. We also calculated the electronic structures with the DV-X-alpha method. In the total DOS curves for the equilibrium adsorption geometry, four peaks located at 8.77, 7.25, 6.02 and 5.09 eV below E(F) are found. They are determined to be the 4-sigma-(a'), 1-pi-(a'), 1-pi-(a") and 5-sigma-(a') levels respectively. The total charge transferred from the substrate to the CN is about 0.51 electrons, which is mainly in to the 5-sigma-orbital.