Singlet-triplet energy gap for trimethylenemethane, oxyallyl diradical, and related species: Single- and multireference computational results

Toru Saito, Satomichi Nishihara, Shusuke Yamanaka, Yasutaka Kitagawa, Takashi Kawakami, Satoru Yamada, Hiroshi Isobe, Mitsutaka Okumura, Kizashi Yamaguchi

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

We have investigated the through-bond exchange interactions in three non-Kekulé hydrocarbon diradicals on the basis of single- and multireference coupled cluster and related broken-symmetry (BS) methods. The singlet-triplet energy gap (S-T gap) and diradical characters for these species are evaluated. It is found that the spin contamination involved in the BS solutions is non-negligible and the approximate spin-projection method greatly improves the usual BS solutions. As for Mukherjee's state-specific multireference coupled cluster (MkMRCC) computations, the size-consistent correction with the UHF localized natural orbitals (ULO) is useful to obtain the qualitatively correct 2J values.

Original languageEnglish
Pages (from-to)739-748
Number of pages10
JournalTheoretical Chemistry Accounts
Volume130
Issue number4-6
DOIs
Publication statusPublished - Dec 1 2011
Externally publishedYes

Keywords

  • Broken-symmetry method
  • Diradical species
  • Multireference coupled cluster
  • Spin-projection method

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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