AB-INITIO MOLECULAR-DYNAMICS STUDY OF ANTIMONY CLUSTERS

We present an ab initio molecular dynamics study of the atomic and electronic structure of SbN (N=2-8 and 12) clusters within the local density approximation and pseudopotential representation of the electron-ion interaction. Simulated annealing calculations have been done for 6-, 7-, 8-, and 12-atom clusters. While for Sb4 a bent rhombus is about 2 eV higher in energy than a regular tetrahedron, we find that it plays an important role in the structure of larger clusters. For Sb8 we obtain two weakly interacting tetrahedra to be of lowest energy. However, this is nearly degenerate with a bent rhombus interacting with a distorted tetrahedron. Further, our calculations suggest a bent rhombus based structure for Sb 12 cluster indicating the observation of Sb4n clusters in Sb vapor condensation cell to be due to abundance of Sb4 clusters. A large gap is found to exist between the highest and the next occupied Kohn-Sham eigenvalues of the lowest energy isomers of 3-, 5-, and 7-atom clusters. This is in agreement with the abundance of cations of these clusters in the laser ablation experiments. © 1995 American Institute of Physics.