Instability in chemical bonds from broken-symmetry single-reference to symmetry-adapted multireference approaches to strongly correlated electron systems

K. Yamaguchi, S. Yamanaka, Hiroshi Isobe, K. Kawakami, Y. Kitagawa, R. Takeda, T. Saito, M. Nishihara, M. Okumura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Citations (Scopus)

Abstract

Theoretical descriptions of strongly correlated electron systems have been investigated from the view point of generalization of molecular orbital (MO) concepts; namely from broken-symmetry (BS) single reference (SR) MO theories to symmetry-adapted (SA) multi-reference (MR) MO theories. Generalized Hartree-Fock (GHF) MO and generalized Kohn-Sham (GKS) DFT methods are first introduced as the BS SR approach, whereas the MR-X (X=configuration interaction (CI), perturbation (PT), coupled-cluster (CC) and density fianctional theory (DFT)) are discussed as the SA MR approach. The quantum resonance (R) of the degenerated BS MO solutions is also examined as a powerful procedure for recovery of the broken spin and spatial symmetries in finite systems. The RBS MO CI has been applied to elucidate electronic structures of triangular and tetrahedral systems with strong spin frustrations. The RBS MO method also gives rise to an approximate spin projection (AP) scheme of the spin-contaminated BS solutions. The natural orbitals (NO) analysis of BS and RBS solutions provides symmetry-adapted (SA) NOs and their occupation numbers, which are useful for construction of complete active space (CAS) for successive MR-X computations. The occupation numbers of NOs are also used to define several chemical indices such as effective bond order (b and B) and unpaired electron density (U), which are common conceptual bridges between BS SR and SA MR methods. Applications of these theoretical methods have been performed for elucidation of chameleonic reactivity of molecular oxygen and transition-metal oxo species, and the nature of chemical bonds in ion-radicals and mixed-valence (MV) iron-sulfiar clusters as typical examples with strongly correlated electron systems.

Original languageEnglish
Title of host publicationAIP Conference Proceedings
PublisherAmerican Institute of Physics
Pages20-29
Number of pages10
Volume1108
DOIs
Publication statusPublished - 2009
Externally publishedYes
Event6th International Conference on Computational Methods in Science and Engineering, ICCMSE 2008 - Hersonissos, Crete, Greece
Duration: Sep 25 2008Sep 30 2008

Other

Other6th International Conference on Computational Methods in Science and Engineering, ICCMSE 2008
CountryGreece
CityHersonissos, Crete
Period9/25/089/30/08

Fingerprint

chemical bonds
broken symmetry
molecular orbitals
symmetry
electrons
occupation
configuration interaction
frustration
reactivity
projection
transition metals
recovery
electronic structure
valence
iron
orbitals
perturbation
oxygen

Keywords

  • BS MO
  • CAS CI
  • CASDFT
  • CASSCF
  • CC
  • CI
  • MR
  • MRDFT
  • MV
  • PT
  • RBS MO
  • SR

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Yamaguchi, K., Yamanaka, S., Isobe, H., Kawakami, K., Kitagawa, Y., Takeda, R., ... Okumura, M. (2009). Instability in chemical bonds from broken-symmetry single-reference to symmetry-adapted multireference approaches to strongly correlated electron systems. In AIP Conference Proceedings (Vol. 1108, pp. 20-29). American Institute of Physics. https://doi.org/10.1063/1.3117132

Instability in chemical bonds from broken-symmetry single-reference to symmetry-adapted multireference approaches to strongly correlated electron systems. / Yamaguchi, K.; Yamanaka, S.; Isobe, Hiroshi; Kawakami, K.; Kitagawa, Y.; Takeda, R.; Saito, T.; Nishihara, M.; Okumura, M.

AIP Conference Proceedings. Vol. 1108 American Institute of Physics, 2009. p. 20-29.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Yamaguchi, K, Yamanaka, S, Isobe, H, Kawakami, K, Kitagawa, Y, Takeda, R, Saito, T, Nishihara, M & Okumura, M 2009, Instability in chemical bonds from broken-symmetry single-reference to symmetry-adapted multireference approaches to strongly correlated electron systems. in AIP Conference Proceedings. vol. 1108, American Institute of Physics, pp. 20-29, 6th International Conference on Computational Methods in Science and Engineering, ICCMSE 2008, Hersonissos, Crete, Greece, 9/25/08. https://doi.org/10.1063/1.3117132
Yamaguchi K, Yamanaka S, Isobe H, Kawakami K, Kitagawa Y, Takeda R et al. Instability in chemical bonds from broken-symmetry single-reference to symmetry-adapted multireference approaches to strongly correlated electron systems. In AIP Conference Proceedings. Vol. 1108. American Institute of Physics. 2009. p. 20-29 https://doi.org/10.1063/1.3117132
Yamaguchi, K. ; Yamanaka, S. ; Isobe, Hiroshi ; Kawakami, K. ; Kitagawa, Y. ; Takeda, R. ; Saito, T. ; Nishihara, M. ; Okumura, M. / Instability in chemical bonds from broken-symmetry single-reference to symmetry-adapted multireference approaches to strongly correlated electron systems. AIP Conference Proceedings. Vol. 1108 American Institute of Physics, 2009. pp. 20-29
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