Theoretical calculation of vibrations of adsorbed species

The chemisorption of oxygen on Lithium, Aluminum, Nickel and Copper surfaces has been investigated using the ab initio Hartree-Fock cluster model. These substrates have the possibility for different bonding in that Li is a simple s metal, Al an s, p and Ni(Cu) an s, p, d metal. In all cases, we have calculated binding energy curves as a function of the oxygen-metal distance. Using these curves, we have derived oxygen-metal normal vibrational frequencies, and the equilibrium bond distance. We have compared the calculated vibrational energy with electron energy loss spectroscopic (EELS) data for Al and find a satisfactory agreement. We discuss O adsorbed on Ni(100) for which coverage dependent loss peaks have been reported but no generally acceptable interpretation exists to date.