signature=776c92af5d9bf1278a4d8e98fc1b17a9,Predictions of special signatures of fullerenes. Second-o...

摘要：

It is argued that pseudo closed-shell fullerenes (those with two electrons in every occupied bonding orbital but with a bonding LUMO in Hückel theory) often fulfil the conditions for second-order Jahn–Teller distortion. Semiempirical (MNDO, AM1 and PM3) calculations on isomers of C44, C68and C92 yield optimal structures of C2 symmetry (C44) and D2 symmetry (C68 and C92), rather than the maximal possible T symmetry while C56 and a second C92 isomer give structures of S4 rather than the maximal Td symmetry. The distortions to lower symmetry are accompanied by a smoothing out of inequalities in atomic charge. Tetrahedral (Td) C84 has a properly closed shell in Hückel theory and shows no loss of symmetry in a semiempirical calculation. Consequences of the distortions for spectroscopic signatures are discussed.

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