Nature of Binding in Small Metal Clusters

摘要

The ab initio many-body model potentials for the Li_3 and Be_3 clusters are constructed. Analysis of exchange and dispersion contributions allows to elucidate the nature of binding in these clusters. The Li_3 clusters are formed by the covalent chemical bonding, although the interstitial orbitals revealed in the spin-coupled studies of Gerratt and coauthors make the binding picture in the Li_N clusters far enough from the convential covalent picture. The binding in the Be_3 clusters has a mixed physical and chemical nature: it is provided by the additive van der Waals forces and the nonadditive three-body exchange forces.