APPLICATION OF THE MANY-BODY EXPANSION PO TENTIAL-ENERGY FUNCTIONS TOTHE STUDY OF GROUP-IV ATOMIC MICROCLUSTERS .3. STRUCTURES AND STABILITIES OF GERMANIUM MICROCLUSTERS

A many-body expansion potential energy function parameterised to the p roperties of solid germanium is used to study the structures and stabi lities of germanium microclusters. Close-packed structures are found f or small clusters (Ge2- Ge14), consisting of exclusively four-membered butterfly rings. Shell optimization of the common cubic structures (d iamond, sc, bcc, and fcc) indicates that the distorted sc, fcc, and bc c shell clusters with the out-most shells compressed most severely are more stable than diamond-type shell clusters and that diamond structu res become more stable only for the clusters containing several hundre ds of atoms.