MANY-BODY INTERACTIONS, SYMMETRY-ADAPTED PERTURBATION-THEORY AND CHEMICAL BONDING IN BERYLLIUM CLUSTERS

The general formulae for the decomposition of many-body interaction en ergies in the double SAFT and the ab initio model potential for the Be -3 cluster are presented. The analysis of exchange and dispersion cont ributions to the model potential allows to elucidate the nature of bin ding in beryllium clusters. Two kind of stabilizing forces are respons ible for binding: the additive local van der Waals forces and the nona dditive delocalized exchange forces.