EHMO CALCULATION FOR HYDROGEN ADSORPTION ON NI AND CU ATOM CLUSTERS

The extended Hückel molecular orbital theory is applied to adsorption of atomic hydrogen on (111), (110) and (100) surfaces of Ni and Cu atom clusters containing up to ten atoms. The edge (or surface) effects play important roles in electronic populations of atoms in clusters and in adsorption energies. The edge atoms of clusters are the preferred sites for the H adatoms. From the orbital symmetry considerations, it is concluded that the edge Ni atoms compose active sites for a catalytic reaction but the edge Cu atoms do not