Growth behavior, electronic structure, and vibrational properties of SinY anion clusters (n=4-20): Metal atom as linker and endohedral dopant

We report results of ab initio calculations on Y-doped anion Si-n clusters with n = 4-20. Our results suggest two growth behaviors in the intermediate range of n = 8 and 20: (1) There is the formation of linked clusters in which a metal atom links two subclusters and (2) where silicon atoms form a cage structure and the metal atom is inside the cage to produce endohedral cages of silicon clusters. The cluster structures have been identified by comparing the calculated spectra of the electronic states with the photoemission spectra on anion clusters. Our results suggest that in some cases a higher energy isomer may be present in experiments. We report the calculations of the infrared and Raman spectra as well as the dipole moments, electron affinity, and polarizability that could provide other ways of identifying the growth behavior in these clusters.