Energetics and electronic structures of hydrogenated metal clusters

Equilibrium geometries, binding energies, and stability of metal clusters (Li and Y) containing hydrogen atoms have been calculated using the self-consistent-field--linear-combination-of-atomic-orbitals-- molecular-orbital method. The exchange and correlation energies are treated both using the density-functional and the Hartree-Fock--M\"oller-Plesset schemes. The results are compared with the corresponding bulk hydrides to see if the interaction of hydrogen with a cluster is significantly different from that with the corresponding crystal. For these metals (Li,Y) which form stable hydrides, the hydrogen uptake by a cluster is found not to exceed that in the bulk. The hydrogen-induced levels and the ionization potentials, on the other hand, are found to depend strongly on the hydrogen content of the cluster.