Calculations of hydrogen chemisorption energies on optimized copper clusters

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