Structural growth behavior and polarizability of Cd_n Te _n (n=1-14) clusters

The lowest-energy structures of Cd_n Te_n (n=1-14) clusters have been studied by an unbiased simulated annealing search using first-principles molecular dynamics along with local optimization of "handmade" structures using density functional theory. After n≥6, three-dimensional cage geometries are the lowest-energy configurations. Two families of low-lying structures, hollow cages, and endohedral or core-shell cages are found. The endohedral cages begin to appear from n=10, and they become more energetically preferred than the hollow cages for n≥12. Cd₁₃ Te₁₃ with the core-shell cage structure is particularly stable. At the same size, the hollow cages possess smaller dipole moments and larger polarizabilities than the endohedral ones. The polarizabilities for the three-dimensional cage structures are insensitive to cluster size. The anisotropies in the polarizabilities mirror the anisotropies in cluster shapes.