Theoretical studies of metal clusters and of chemisorption on metals

The results of different theoretical methods are compared in the analysis of three illustrative problems. The methods involved are: local density functional (LDF), Xα, Hartree–Fock, generalized valence bond (GVB), and configuration interaction (CI). The three problems considered are: (1) the bonding of Mo2 and Cr2, (2) the photoelectron spectra of Cu clusters, and (3) the chemisorption of N2 on Ni. The comparisons provide new insights both into these problems and into the physical content of the methods per se. In the case of the comparison of studies on Cu clusters, one is led to reinterpret the nature of photoemission from narrow d bands and its relationship to conventional band theory.