Methyl chemisorption on Ni(111) and C-H-M multicentre bonding: a density functional theory study

Density functional theory has been used to study the adsorption of CH3 on N i(111). CH3 is found to adsorb strongly at all four high symmetry sites of the Ni(111) surface. Calculated adsorption energies of CH3 on the different sites are in the following order: hcp approximate to fcc>bridge>top. The b onding and structures of CH3 on the different sites are analysed in detail. An important factor, namely three-centre bonding between carbon, hydrogen and nickel which contributes to the 'soft' C-H vibrational frequency of CH3 on Ni(111), and may determine the preferred chemisorption site, is stresse d. (C) 1999 Elsevier Science B.V. All rights reserved.