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Theoretical investigation of stabilities and optical properties of Si12C12 clusters.

Authors
  • Duan, Xiaofeng F
  • Burggraf, Larry W
Type
Published Article
Journal
The Journal of Chemical Physics
Publisher
American Institute of Physics
Publication Date
Jan 21, 2015
Volume
142
Issue
3
Pages
34303–34303
Identifiers
DOI: 10.1063/1.4905542
PMID: 25612705
Source
Medline
License
Unknown

Abstract

By sorting through hundreds of globally stable Si12C12 isomers using a potential surface search and using simulated annealing, we have identified low-energy structures. Unlike isomers knit together by Si-C bonds, the lowest energy isomers have segregated carbon and silicon regions that maximize stronger C-C bonding. Positing that charge separation between the carbon and silicon regions would produce interesting optical absorption in these cluster molecules, we used time-dependent density functional theory to compare the calculated optical properties of four isomers representing structural classes having different types of silicon and carbon segregation regions. Absorptions involving charge transfer between segregated carbon and silicon regions produce lower excitation energies than do structures having alternating Si-C bonding for which frontier orbital charge transfer is exclusively from separated carbon atoms to silicon atoms. The most stable Si12C12 isomer at temperatures below 1100 K is unique as regards its high symmetry and large optical oscillator strength in the visible blue. Its high-energy and low-energy visible transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer.

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