Optical properties of geometrically optimized graphene quantum dots |
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| Affiliation: | 1. Department of Theoretical Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland;2. Department of Physics, Advanced Research Complex, 25 Templeton Str., University of Ottawa, Ottawa, Ontario, Canada K1N 6N5;1. Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Cameroon;2. Department of Physics, Higher Teachers'' Training College, The University of Maroua, PO BOX 55 Maroua, Cameroon;1. Department of Applied Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China;2. Institute of Applied Physics and Materials Engineering, FST, University of Macau, China;1. Laboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna, Université de Carthage, Tunisia;2. Faculty of Chemistry, University of Wroclaw, 14, Joliot Curie, 50-383 Wroclaw, Poland;3. Department of Chemical and Pharmaceutical Sciences and Center for Structural Diffractometry, Via Fossato di Mortara 17, I-44121 Ferrara, Italy;4. Laboratoire de Chimie Organométallique de Surface (LCOMS), Ecole Supérieure de Chimie Physique Electronique, 69626 Villeurbanne Cedex, France;1. Laboratory of Heteroatom Organic Chemistry, University of Carthage, Faculty of Sciences of Bizerte, 7021, Jarzouna, Tunisia;2. Laboratoire de Chimie des Matériaux, Université de Carthage, Faculté des Sciences de Bizerte, 7021, Zarzouna, Tunisia;3. Laboratoire de Chimie Organométallique de Surface (LCOMS), Ecole Supérieure de Chimie Physique Electronique, 69626, Villeurbanne Cedex, France;4. Department of Chemistry, BOX 351700 University of Washington Seattle, WA, 98195, USA;5. Graduate School of Natural Science, Nagoya City University, Yamanohata, Mizuho-cho, Mizuho-ku, Nagoya, 467-8501, Japan |
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| Abstract: | We derive effective tight-binding model for geometrically optimized graphene quantum dots and based on it we investigate corresponding changes in their optical properties in comparison to ideal structures. We consider hexagonal and triangular dots with zigzag and armchair edges. Using density functional theory methods we show that displacement of lattice sites leads to changes in atomic distances and in consequence modifies their energy spectrum. We derive appropriate model within tight-binding method with edge-modified hopping integrals. Using group theoretical analysis, we determine allowed optical transitions and investigate oscillatory strength between bulk–bulk, bulk–edge and edge–edge transitions. We compare optical joint density of states for ideal and geometry optimized structures. We also investigate an enhanced effect of sites displacement which can be designed in artificial graphene-like nanostructures. A shift of absorption peaks is found for small structures, vanishing with increasing system size. |
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| Keywords: | Graphene quantum dots Optical properties |
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