Hueckel Model for Small Metal Clusters. 2. Orbital Energies, Shell Structures, Ionization Potentials, and Extrapolation to the Bulk Limit

摘要

We analyze the results of HMO calculations (this paper and its preceding companion) for the neutral and cation alkali-like metal clusters, M2-M14. The filled HMO energy levels develop as well-separated energy shells 1s, 1p, 1d, ---where s, p and d denoted the global nodal character of the Huckel orbitals. The HMO energy shells decrease in energy with increasing cluster size. By smoothly fitting the HMO orbital energies, we obtain trends in (a) atomization energies (b) relative cluster stabilities and (c) ionization potential which are highly reminiscent of those derived from Jellium calculations. The HMO atomization energies are within 15% of the experimental results for bulk Li Cs. Thus we are able to unify within the single framework of HMO theory the quantum, Jellium and droplet models for alkali metal clusters. For the neutral clusters, HMO and Local-Spin-Density atomization energies agree to within ca. 4%.