First-principles study of adsorption of methyl, coadsorption of methyl and hydrogen, and methane dissociation on Ni(1Â 0Â 0)

The adsorption of methyl on Ni(1 0 0) has been investigated using density functional theory calculations based on plane-wave expansion and pseudo-potential treatment. It was found that the bridge site with one of the hydrogen atoms near top site is most favorable. The calculated C-H symmetric stretching frequencies for the preferred bridge site showed a significant mode softening, thanks to the three-center bonding between C-H and Ni. The coadsorption of methyl and hydrogen on Ni(1 0 0) has also been calculated. The methyl at a bridge site with coadsorbed hydrogen at a hollow site was found to be preferred. In addition, the dissociation of methane on Ni(1 0 0) has been studied and the barrier height was found to be 0.73 eV, in good agreement with the recent experimental value of 0.61 eV.