BOND PROPERTIES OF BE(3-7) CLUSTERS

Geometries, binding energies, and bonding properties have been investi gated for the Be-3-7 clusters with ab initio molecular orbital theory using double (6-31G) and triple [6-311(+)G*] zeta-basis sets with inc lusion of the effects of electron correlation estimated with the Molle r-Plesset perturbation (up to full MP4) and coupled cluster (QCI) theo ries. The geometries and binding energies suggest that the single-refe rence approach gives already reasonable results for Be-5. For the larg er clusters Bader's electron density analyses reveals small concentrat ions of charge within groups of three Be atoms.