Electronic structures and magic numbers of small silver clusters: A many-body perturbation-theoretic study

The formalism of second-order many-body perturbation theory has been applied to investigate the electronic and geometric structures of neutral, cationic, and anionic Ag{sub n} (n=5-9) clusters. Hay-Wadt relativistic effective core potentials replacing the 28 core electrons and a Gaussian basis set have been used. Full geometry optimizations of topologically different clusters and clusters belonging to different symmetry groups have been carried out. The neutral silver clusters prefer planar geometry up to n=6 and the charged clusters prefer three-dimensional geometry from n=6. Binding energies, ionization potentials, electron affinities, and fragmentation energies of the optimized clusters have been compared with other experimental and theoretical results available in the literature. Based on different criteria, we predict the eight-atom silver cluster to be a magic-number cluster.