Structure and electronic property of Sin (n=20-40 and 45) clusters

The lowest-energy structures of Sin clusters (n=20-40 and 45) are obtained with a genetic algorithm and nonorthogonal tight-binding (NTB) model. We find that the atoms are organized into two shells. The outer one forms a distorted cage and the inner one containing one atom or a few core atoms. Sin clusters change to prolate-spherical from n=24 and change to oblate-spherical structures from n=29 and change to near-spherical structures from n=32. The binding energies increase with cluster size n smoothly in this range and no magic number is found in this clusters range. All of the curves of the density of states (DOS) profiles are very similar. Only slight variations occur between profiles of neighboring clusters. The band gap decreases with the increasing of clusters size.