Equilibrium Geometries, Stabilities, and Electronic Properties of the Bimetallic Ag2-doped Sin (n=1 – 11) Clusters: A Density-Functional Investigation

An ab initio method based on the density functional theory has been employed to investigate the behaviours of the bimetallic Ag2-doped silicon clusters at a size of n = 1 - 11. The possible geometrical configurations, growth-pattern behaviours, stabilities, energy gaps, and electronic properties are presented and discussed. The optimized geometries reveal that the silicon atom surface-capped and silver atom substituted 3D structures are dominant growth patterns. The calculated averaged binding energy, fragmentation energy, and the second-order difference of energy manifest that the most stable structures of Ag2Sin (n = 1 - 11) clusters are Ag2Si2 and Ag2Si5 isomers, which is in qualitative agreement with the AgSin clusters. In addition, the gap between highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) exhibits that the Ag2Si3 and Ag2Si5 isomers have dramatically enhanced chemical stability. Natural population analysis shows that the charge-transfer phenomena are coincidence with the AgSin clusters but different from Mo2Sin systems. Furthermore, the dipole moments of stable Ag2Sin (n = 1 - 11) display a pronounced odd-even oscillation with the number of silicon atoms.