A density functional study of the adsorption of CO on Rh(111)

Adsorption of CO on Rh{111} has been studied by means of density functional calculations within the cluster model approach. Optimized structures and C-O stretching frequencies appear to be in good agreement with experiment and they permit the confirmation of the structural model suggested by Beutler et al. ( A. Beutler, E. Lundgren, R. Nyholm, J. N. Andersen, B. Setlik and D. Heskett, Surf. Sci., 1997, 371, 381, A. Beutler, E. Lundgren, R. Nyholm, J. N. Andersen, B. Setlik and D. Heskett, Surf. Sci., 1998, 396, 117) using HRCLS. Vibrational frequency shift dependence on surface coverage has been analyzed in terms of dipole dipole coupling and chemical effects. Furthermore, we discuss a third mechanism that is likely to be responsible for the shift to higher frequencies at high coverage regime