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CuSi_n与CuSi_n~-(n=4～10)团簇电子结构和光学性质的理论研究（英文）.docx

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CuSi_n与CuSi_n~-(n=4～10)团簇电子结构和光学性质的理论研究（英文） TheoreticalStudyonElectronicStructureandOpticalPropertiesofCuSi_nandCuSi_n~-(n=4-10)Cluster Clusterscienceisarapidlygrowingfieldthathassparkedagreatdealofinterestduetotheuniquepropertiesexhibitedbysmallclustersofatoms.Thesepropertiesarisefromthequantumconfinementoftheelectronsintheclusters.Inthispaper,wepresentatheoreticalstudyontheelectronicstructureandopticalpropertiesofCuSi_nandCuSi_n~-(n=4-10)clusters. Theelectronicstructureoftheclusterswascomputedusingdensityfunctionaltheory(DFT)withtheB3LYPfunctionalandthebasissetsof6-311+G**.TheoptimizedgeometriesfortheclusterswerecalculatedatthesamelevelusingGaussian09.TheresultsshowedthatboththeCuSi_nandCuSi_n~-clustershaveadistortedoctahedralstructure.TheSiatomsarearrangedinacubewithaCuatomatthecenter,andeachSiatomisbondedtotwoCuatoms.Thecalculatedbondlengthsandenergiesareconsistentwiththereportedexperimentalresults. Theelectronicstructureoftheclusterswasanalyzedbystudyingthefrontiermolecularorbitals(FMOs)andthehighestoccupiedmolecularorbital(HOMO)–lowestunoccupiedmolecularorbital(LUMO)gaps.TheFMOsoftheclustersshowthatthehighestoccupiedmolecularorbitalsareprimarilylocalizedontheSiatoms,whilethelowestunoccupiedmolecularorbitalsaremainlylocatedontheCuatoms.TheHOMO-LUMOgapsdecreaseasthesizeoftheclustersincreases.Thiscanbeattributedtothequantumconfinementeffect,whichincreasestheenergyoftheelectronicstatesasthesizeoftheclusterdecreases. Theopticalpropertiesoftheclusterswerestudiedbycalculatingtheabsorbancespectrausingthetime-dependentdensityfunctionaltheory(TD-DFT)method.Theresultsshowedthattheclustershavestrongabsorbanceintheultravioletregionandweakabsorbanceinthevisibleregion.Theabsorbancespectraoftheanionicclusters(CuSi_n~-)arered-shiftedcomparedtothecorrespondingneutralclusters.Thisisduetotheadditionalelectronpresentintheanionicclusters,whichincreasesthepolarizationoftheclustersandshiftstheabsorbancespectratowardslongerwavelengths. Inconclusion,thisstudyprovidesinsightintotheelect