Size-dependent structural and electronic properties of Tin clusters (n≤100)

The results of a genetic-algorithms search for structures of titanium clusters with up to 100 atoms are presented. An empirical pair potential has been used in describing the interatomic interactions during the genetic-algorithms search. The resulting global-minimum structures have been used as starting geometries of geometry optimizations using a density-functional tight-binding method. Structural, energetic, and electronic properties are analysed and compared. Special attention is paid to the size dependence of the properties, including point groups, radial atomic distributions, bond lengths, moments of inertia, stability, Mulliken populations and frontier orbitals. Similarity functions are defined to facilitate the analysis of the growth of the clusters. It turned out that the empirical potential favours highly symmetric geometries, that exhibit small distortions upon relaxation using the electronic-structure method. Some larger, particularly stable clusters are fragments of the hcp bulk structure but an overall transition to bulk structure cannot be seen below 100 atoms