Theoretical Study of the Relationship between the Geometry and the Orbital Hybridization in the CuAln− (n = 11–13) Cluster

The relationship between the geometric features and electronic behavior of CuAln− (n = 11–13) clusters was investigated using the B3LYP method with 6-311+G* basis set. The electronic behaviors were analyzed by using the partial density of states (PDOS). The geometric structures were classified on the basis of the cluster framework and the position of a Cu atom. The Cu atom is added to the surface of the Al framework in Type I. The Cu atom locates at the center or inside of the cluster in the Type II. In addition, the double-wheel type CuAl11− (Type III) was examined. Few d-orbital components of Cu are included in the molecular orbitals (MOs) in the peaks higher than −3.5 eV. The d-orbital of Cu contributes to the MOs in the region lower than −3.5 eV. The sp+d and s-p+d bondings occur in Type I. The s-p+d bonding fundamentally occurs in Type II. The s-p+d bonding of Type II is separated into the bonding and anti-bonding of the d and s-p components with the increasing number of Als. In Type III, the contribution of the d-component of Cu to the orbital hybridization is small.