Operator Projection Method Applied to the Single-Particle Green's Function in the Hubbard Model

Shigeki Onoda*, Masatoshi Imada

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


A new non-perturbative framework for many-body correlated systems is formulated by extending the operator projection method (OPM). This method offers a systematic expansion which enables us to project into the low-energy structure after extracting the higher-energy hierarchy. This method also opens a way to systematically take into account the effects of collective excitations. The Mott-Hubbard metal-insulator transition in the Hubbard model is studied by means of this projection beyond the second order by taking into account magnetic and charge fluctuations in the presence of the high-energy Mott-Hubbard structure. At half filling, the Mott-Hubbard gap is correctly reproduced between the separated two bands. Near half filling, strongly renormalized low-energy single-particle excitations coexisting with the Mott-Hubbard bands are shown to appear. The significance of the momentum-dependent self-energy in the results is stressed.

Original languageEnglish
Pages (from-to)632-635
Number of pages4
Journaljournal of the physical society of japan
Issue number3
Publication statusPublished - 2001 Mar
Externally publishedYes


  • Hubbard model
  • Metal-insulator transition
  • Projection operator

ASJC Scopus subject areas

  • General Physics and Astronomy


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