Theoretical investigation on the geometries and electronic properties of cesium-silicon CsSi n (n=2-12) clusters

The structures, relative stabilities, and electronic properties of pure Si (n) and Cs-doped silicon clusters (n = 2-12) are systematically investigated using the density functional theory at the B3LYP level. The optimized structures indicated that the lowest-energy structures of CsSi (n) are similar to those of pure Si (n) clusters and prefer the 3-dimensional configuration for n = 3-12. The relative stabilities of CsSi (n) clusters are analyzed based on the averaged binding energy, fragmentation energy, second-order energy difference, and HOMO-LUMO energy gap. It is found that CsSi6 and CsSi9 are the magic clusters, and the doping of Cs atom reduces the chemical stabilities of Si (n) frame. The Mulliken population analysis pointed out that the charges in the corresponding CsSi (n) clusters always transfer from Cs atom to Si (n) host in the range of 0.80-0.91 electron. In addition, the partial density of states, infrared, and Raman spectra is discussed.