Low-Energy Structures and Electronic Properties of Large-Sized Si-N Clusters (N=60, 80, 100, 120, 150, 170)

摘要

Global search based on semiempirical and first-principles calculations has been performed to determine the lowest-energy structures of large-sized silicon (Si) clusters: Si-N (N = 60, 80, 100, 120, 150, 170). We found that the stuffed-cage structural motif is dominant for these large clusters, where the ratio of the number of surface atoms to core atoms agrees well with a previously proposed space-filling model up to N = 120 and the structures of outer cages contain not only the majority of the pentagonal and hexagonal rings but also a few seven-membered or eight-membered rings. Triple-layered stuffed-cage structures are found for Si-150 and Si-170. Based on the lowest-energy structures, the physical properties of Si clusters (including binding energy, ionization potential, adiabatic detachment energy, electronic gap, and photoelectron spectrum) are computed and compared with the experimental data. For the first time, our theoretical study provides a fundamental picture for large Si clusters up to 170 atoms.