Small Al clusters. II. Structure and binding in Aln (n=2-6, 13)

The structure and stability of aluminum clusters containing up to six atoms have been studied using correlated wave functions and extended basis sets. The lowest energy structure is planar for Al₄ and Al₅, but three dimensional for Al₆. The icosahedral, hcp, fcc, and two planar structures of Al₁₃ were considered at the SCF level. The lowest energy structure is the icosahedron, but the planar structures are fairly low lying even in this case. A simplified description using two- and three-body interaction potentials is found to agree well with the ab initio structures and binding energies.