SIZE DEPENDENCE OF THE IONIZATION-POTENTIALS OF CD CLUSTERS

The size dependence of the ionization potentials of cadmium clusters is studied by a localized-orbital theory based on the tight-binding approximation. The total density of state (DOS) of the Cd(n) clusters is obtained by means of the moment expansion method in order to obtain the Fermi energy of the system. The Fermi energy E(F) combined with the correction of the classical conducting sphere droplet (CSD) model are used to calculate the ionization potential (IP) of the cluster. The theoretical values reproduce the experimental results quite well. The size dependence of the ionization potential shows a rapid convergence towards the bulk limit and obey the 1/R law provided by the CSD model in general, indicating that the small Cd clusters have been already metallic-like.