Theoretical investigation of the relaxed geometry in the first singlet Bu excited state of polyacetylene oligomers

J. L. Brédas*, J. M. Toussaint

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

We present the results of calculations carried out at both Pariser-Parr-Pople and ab initio split-valence basis set levels, aimed at finding the nature of the relaxed geometry configuration in S2 which is the first singlet one-photon optically allowed Bu excited state of three polyene molecules: hexatriene, decapentaene, and tetradecaheptaene. We investigate as a function of chain length the relative stabilities of two types of geometry configuration in the excited state: one configuration derives from the use of traditional bond order-bond length relationships; the other configuration comes from the explicit consideration of the electron-lattice coupling and leads to the formation of a soliton-antisoliton pair. The latter configuration is found to correspond to a stable situation in polyenes containing over ten carbon atoms and provides a smooth evolution to the long chain (polyacetylene) properties.

Original languageEnglish (US)
Pages (from-to)2624-2629
Number of pages6
JournalThe Journal of Chemical Physics
Volume92
Issue number4
StatePublished - 1990
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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