Theoretical investigation of growth, stability, and electronic properties of beaded ZnO nanoclusters

Abstract

A beaded ZnO nanocluster as a novel stand-alone system has been introduced by interconnecting different numbers of highly stable (ZnO)₁₂ basic units. Geometries, stabilities, electronic properties, and vibrational spectra of the beaded ZnO nanoclusters have been systematically studied by using density functional theory. The results indicate that the beaded ZnO nanoclusters with large binding energies have high stabilities during their growth process. The energy gaps of the (ZnO)_12×n nanoclusters (n ≥ 3) show a relatively slow decrease, indicating that the energy gaps are insensitive to the cluster size for the large clusters. The low-lying highest occupied molecular orbital and the high-lying lowest unoccupied molecular orbital are observed to shift to the top of the low energy levels and the bottom of the high energy levels, respectively, leading to the reduction of the energy gap. In addition, by calculating its energy gap, vertical ionization potential, adiabatic electron affinity, and chemical hardness, we find that the beaded ZnO nanocluster has a higher chemical reactivity during its growth process. Vibrational frequencies of ZnO clusters and nanoclusters are also discussed in detail.