Correlation of adsorption energy with surface structure: ethylene adsorption on Pd surfaces

First principles density functional theory calculations have been performed for the chemisorption of ethylene on the {1 1 1}, {1 0 0} and {1 1 0} surfaces of Pd. On all the three low-index surfaces, the most stable site and geometry for C2H4 is that where the C–C bond axis is parallel to the surface along the bridge site. The calculated binding energies follow the trends: Eads,111<Eads,100<Eads,110. The results show that the surface relaxation induces a significant shift in the level of the metal d-band. The calculated adsorption energies are only linearly correlated with the d-band centre of the surface atoms for the unrelaxed structure.