Density-functional calculations of atomic and molecular adsorptions on 55-atom metal clusters: Comparison with (1Â 1Â 1) surfaces

Density-functional calculations were performed to study the molecular (CO and O2) and atomic (H and O) adsorptions on four icosahedral clusters composed of 55 atoms (Pt55, Au55, Cu55 and Pt42Ru13) and corresponding (1 1 1) flat surfaces. It was found that all adsorption energies become larger on clusters than on (1 1 1) surfaces. It was also found that the site preference of adsorption on Au55 is quite different from that on Pt55.