Extended Hartree-Fock (EHF) theory of chemical reactions VI: Hybrid DFT and post-Hartree-Fock approaches for concerted and non-concerted transitions structures of the Diels-Alder reaction

Hiroshi Isobe, Y. Takano, Y. Kitagawa, T. Kawakami, S. Yamanaka, K. Yamaguchi, K. N. Houk

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Activation barrier heights for concerted and non-concerted transition structures between butadiene and ethylene have been calculated by the broken-symmetry Hartree-Fock (HF), QCISD(T), and CCSD(T) methods with and without approximate spin projection, and the spin-restricted CASCI, CASSCF UNO MP2 and MR MP2 methods. They also have been calculated by the density functional theory (DFT) and hybrid DFT (HDFT) methods such as B2LYP and B3LYP. The reliability and utility of the HDFT methods have been investigated, and compared with the post-HF and MR MP2 results. The information entropy and related electron correlation indices also have been examined in relation to the polyradical character of the transition structures. Implications of the present results are discussed concerning the applicability of HDFT to large systems.

Original languageEnglish
Pages (from-to)717-727
Number of pages11
JournalMolecular Physics
Issue number6
Publication statusPublished - Mar 20 2002
Externally publishedYes


ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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