| Abstract
| - We performed first-principles calculations on silica nanorings (NRs) designed via the assembly of two- (2MR), three- (3MR), four- (4MR), and six-membered rings (6MR) in a number of different ways. The stable configurations, energetics, and electronic structures of these NRs are presented. The most stable configurations were found to be size-dependent and to possess different structural features at different size ranges. For small-size silica NRs (SiO2)n with n< 12, the configurations with 2MR−3MR hybrid structures (2−3MR-NRs) were energetically most stable. For 12 < n< 22, the NRs formed from linked 2MRs (2MR-NRs) became most favorable. For n> 22, the configurations composed of uniformly hybrid 2MRs and 4MRs (2−4MR-NRs) were the most stable structures. The 2−4MR-NRs had the narrowest HOMO−LUMO gaps, which decreased with decreasing n.
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