AN ANALYTICAL REPRESENTATION OF THE MODEL POTENTIAL FOR BERYLLIUM TRIMERS

A 2- and 3-body model potential for the Be-3 cluster has been construc ted. The parameters of the 2- and 3-body terms were fitted separately to the corresponding nb initio many-body energies calculated at the MP 4 level. The study of the 3-body component in different triangle confo rmations reveals that the 3-body forces determine the magnitude of the interaction energy in a relatively large region of distances and angl es. The analysis of exchange and dispersion contributions makes it pos sible to elucidate the nature of binding in the Be-3 cluster.