CALCULATIONS OF HYDROGEN CHEMISORPTION ENERGIES ON OPTIMIZED COPPER CLUSTERS

Hydrogen chemisorption on geometry optimized copper clusters with up t o nine copper atoms has been studied using both all-electron and one-e lectron effective core potential methods. The chemisorption energy on the odd clusters are of the order of 20 kcal/mol higher than on the ev en clusters, in marked contrast to previous results on the correspondi ng lithium clusters where the odd-even oscillations are much smaller. The difference between lithium and copper clusters is explained in ter ms of both a larger effect of geometry relaxation and a larger tendenc y to form s-p hybrids in the lithium case.