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Optical properties of nanoclusters from time-dependent density-functional theory

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Puska, Martti, Prof.
dc.contributor.author Koponen, Laura
dc.date.accessioned 2012-08-24T08:02:10Z
dc.date.available 2012-08-24T08:02:10Z
dc.date.issued 2010
dc.identifier.isbn 978-952-60-3129-3 (electronic)
dc.identifier.isbn 978-952-60-3128-6 (printed) #8195;
dc.identifier.issn 1797-9609
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/4772
dc.description.abstract The ground state properties of a quantum-mechanical many-electron system can be effectively modeled by its total electron density only, which is the key idea of the density-functional theory (DFT) methods. However, electronic excitations to higher energy states are not adequately described by the standard DFT formalism. To model the optical properties, for example, absorption and emission and response to time-dependent fields such as laser fields, the extension to time-dependent DFT (TDDFT) has become a popular method. In this Thesis, the TDDFT methods are utilized to calculate the optical properties of various nanostructures including fullerenes and fullerene derivatives, silicon nanocrystals and metal-polymer hybrid structures. The main focus is in the determination of their photoabsorption spectra using a real-space implementation of TDDFT. By these calculations we study how different structural variations and changes in the chemical environment affect the electronic and optical properties of the materials. For carbon and boron nitride fullerenes, variations in their size, geometry and doping are found to have a clear impact on their photoabsorption spectra. The results strengthen the view that optical absorption can be effectively used in the experimental characterization of such structures, for example in distinguishing between different isomers. The photoabsorption is observed to be strongly affected by the chemical environment for both silicon nanocrystals and small silver nanoclusters. When silicon nanoclusters are embedded in silica, the size dependence of their absorption edge is found to change due to major changes in the electronic structure. For the silver clusters, the presence of a polymer is found to bring the absorption edge down to the visible range in some of the studied cases. These calculations shed light to the experimental observations of unexpected absorption from such structures in the visible range. en
dc.format.extent Verkkokirja (1330 KB, 39 s.)
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Aalto-yliopiston teknillinen korkeakoulu en
dc.relation.ispartofseries Dissertations of Department of Applied Physics, 161 en
dc.relation.haspart [Publication 1]: Laura Koponen, Martti J. Puska, and Risto M. Nieminen. 2008. Photoabsorption spectra of small fullerenes and Si-heterofullerenes. The Journal of Chemical Physics, volume 128, number 15, 154307, 7 pages. © 2008 American Institute of Physics (AIP). By permission. en
dc.relation.haspart [Publication 2]: Laura Koponen, Lasse Tunturivuori, Martti J. Puska, and Risto M. Nieminen. 2007. Photoabsorption spectra of boron nitride fullerenelike structures. The Journal of Chemical Physics, volume 126, number 21, 214306, 4 pages. © 2007 American Institute of Physics (AIP). By permission. en
dc.relation.haspart [Publication 3]: Laura Koponen, Lasse O. Tunturivuori, Martti J. Puska, and Risto M. Nieminen. 2009. Effect of the surrounding oxide on the photoabsorption spectra of Si nanocrystals. Physical Review B, volume 79, number 23, 235332, 6 pages. © 2009 American Physical Society (APS). By permission. en
dc.relation.haspart [Publication 4]: Laura Koponen, Lasse O. Tunturivuori, Martti J. Puska, and Y. Hancock. 2010. Tunability of the optical absorption in small silver cluster–polymer hybrid systems. arXiv:1003.2183v3 [cond-mat.mtrl-sci]. The Journal of Chemical Physics, accepted for publication. © 2010 by authors and © 2010 American Institute of Physics (AIP). By permission. en
dc.subject.other Physics
dc.title Optical properties of nanoclusters from time-dependent density-functional theory en
dc.type G5 Artikkeliväitöskirja fi
dc.contributor.school Aalto-yliopiston teknillinen korkeakoulu fi
dc.contributor.department Teknillisen fysiikan laitos fi
dc.contributor.department Department of Applied Physics en
dc.subject.keyword time-dependent density-functional theory en
dc.subject.keyword photoabsorption en
dc.subject.keyword nanocluster en
dc.subject.keyword fullerene en
dc.subject.keyword silicon nanocrystal en
dc.identifier.urn URN:ISBN:978-952-60-3129-3
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.supervisor Nieminen, Risto, Prof
local.aalto.digifolder Aalto_67884
local.aalto.digiauth ask

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