Configuration of the surface atoms in AlN (270 ≤ N ≤ 500) clusters

Configuration of the surface atoms in aluminum clusters was investigated based on the structures with global minimum potential energy of some Al clusters in the size range of 270-500. The structures were optimized by the dynamic lattice searching with constructed cores (DLSc) method with the NP-B potential. In the optimized structures, all clusters are identified as truncated octahedra (TO) including three complete TO at Al(260), Al(314), and Al(405). With the model of TO(260) and TO(405), the configurations of the surface atoms in the structures of the clusters from 261 to 314 and from 406 to 459 were investigated. The sites on (100) faces are found to be preferable to those on (111) faces for locating the new atoms with the increase of the cluster size, but for the clusters larger than 405 atoms, the sites on the (111) face are favored when the number of atoms exceeds the site number of a (100) face. Furthermore, the sites on the edge adjoining a (100) face and a (111) face are found to be very important to make a cluster more stable.