### Abstract

The electronic structure of finite and infinite linear, cyclic and Möbius strip polyacenes has been investigated by adopting Hückel and semiempirical schemes. Using the Hückel approach, it turns out that the Möbius belting process modifies the highest occupied molecular orbital (HOMO) - lowest unoccupied molecular orbital (LUMO) gap in such a way its evolution with chain length is similar to the linear polyacenes rather than their cyclic analogs. These results are corroborated at the Austin model 1 (AM 1) level, where the geometry relaxation effects are taken into account. The optimized AM 1 structures show that the Möbius defect is localized and extends over a third of the ring. With respect to the Hückel approach, accounting for geometry distortion at the AM 1 levels results in an increase in the HOMO-LUMO gap of the Möbius strip relative to the linear and cyclic finite-size structures. On the other hand, when including electron-hole correlation at the configuration interaction singles Zerner's intermediate neglect of differential overlap level the behavior with system size of the first excitation energy of cyclic and Möbius polyacenes differs from their linear analogs and leads to smaller singlet excitation energies.

Original language | English |
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Pages (from-to) | 431-436 |

Number of pages | 6 |

Journal | Theoretical Chemistry Accounts |

Volume | 105 |

Issue number | 6 |

DOIs | |

Publication status | Published - 1 May 2001 |

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### Keywords

- Austin Model 1 Energy gap
- Möbius strip
- Polyacenes

### Cite this

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**Möbius strip versus linear and cyclic polyacenes : A Hückel and semiempirical investigation.** / Guillaume, Maxime; Champagne, Benoît; Perpète, Eric A.; André, Jean-Marie.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Möbius strip versus linear and cyclic polyacenes

T2 - A Hückel and semiempirical investigation

AU - Guillaume, Maxime

AU - Champagne, Benoît

AU - Perpète, Eric A.

AU - André, Jean-Marie

PY - 2001/5/1

Y1 - 2001/5/1

N2 - The electronic structure of finite and infinite linear, cyclic and Möbius strip polyacenes has been investigated by adopting Hückel and semiempirical schemes. Using the Hückel approach, it turns out that the Möbius belting process modifies the highest occupied molecular orbital (HOMO) - lowest unoccupied molecular orbital (LUMO) gap in such a way its evolution with chain length is similar to the linear polyacenes rather than their cyclic analogs. These results are corroborated at the Austin model 1 (AM 1) level, where the geometry relaxation effects are taken into account. The optimized AM 1 structures show that the Möbius defect is localized and extends over a third of the ring. With respect to the Hückel approach, accounting for geometry distortion at the AM 1 levels results in an increase in the HOMO-LUMO gap of the Möbius strip relative to the linear and cyclic finite-size structures. On the other hand, when including electron-hole correlation at the configuration interaction singles Zerner's intermediate neglect of differential overlap level the behavior with system size of the first excitation energy of cyclic and Möbius polyacenes differs from their linear analogs and leads to smaller singlet excitation energies.

AB - The electronic structure of finite and infinite linear, cyclic and Möbius strip polyacenes has been investigated by adopting Hückel and semiempirical schemes. Using the Hückel approach, it turns out that the Möbius belting process modifies the highest occupied molecular orbital (HOMO) - lowest unoccupied molecular orbital (LUMO) gap in such a way its evolution with chain length is similar to the linear polyacenes rather than their cyclic analogs. These results are corroborated at the Austin model 1 (AM 1) level, where the geometry relaxation effects are taken into account. The optimized AM 1 structures show that the Möbius defect is localized and extends over a third of the ring. With respect to the Hückel approach, accounting for geometry distortion at the AM 1 levels results in an increase in the HOMO-LUMO gap of the Möbius strip relative to the linear and cyclic finite-size structures. On the other hand, when including electron-hole correlation at the configuration interaction singles Zerner's intermediate neglect of differential overlap level the behavior with system size of the first excitation energy of cyclic and Möbius polyacenes differs from their linear analogs and leads to smaller singlet excitation energies.

KW - Austin Model 1 Energy gap

KW - Möbius strip

KW - Polyacenes

UR - http://www.scopus.com/inward/record.url?scp=0035587434&partnerID=8YFLogxK

U2 - 10.1007/s002140000245

DO - 10.1007/s002140000245

M3 - Article

VL - 105

SP - 431

EP - 436

JO - Theoretical Chemistry Accounts: Theory, Computation, and Modeling

JF - Theoretical Chemistry Accounts: Theory, Computation, and Modeling

SN - 1432-881X

IS - 6

ER -