2009/01/31 by Fusayoshi J. Ohkawa, Takahiro Toyama · 1 citation
Materials Science · Physics and Astronomy · #Electron #Fermi Gamma-ray Space Telescope #Fermi liquid theory #Ground state #Hubbard model #Mott insulator #Mott transition #Organic and Molecular Conductors Research #Physics of Superconductivity and Magnetism #Quantum spin liquid #Rare-earth and actinide compounds #Strongly correlated material #Superexchange #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1143/jpsj.78.124707
published in Journal of the Physical Society of Japan 78(12), 124707 (Physical Society of Japan) · 11 pages, no figure
openalex publication_date 2009/12/10 · arxiv created 2009/12/11 · arxiv updated 2010/01/07 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The ground state of the Hubbard model is studied within the constrained Hilbert space where no order parameter exists. The self-energy of electrons is decomposed into the single-site and multisite self-energies. The calculation of the single-site self-energy is mapped to a problem of self-consistently determining and solving the Anderson model. When an electron reservoir is explicitly considered, it is proved that the single-site self-energy is that of a normal Fermi liquid even if the multisite self-energy is anomalous. Thus, the ground state is a normal Fermi liquid in the supreme single-site approximation (S 3 A). In the strong-coupling regime, the Fermi liquid is stabilized by the Kondo effect in the S 3 A and is further stabilized by the Fock-type term of the superexchange interaction or the resonating-valence-bond (RVB) mechanism beyond the S 3 A. The stabilized Fermi liquid is frustrated as much as an RVB spin liquid in the Heisenberg model. It is a relevant unperturbed state that can be used to study a normal or anomalous Fermi liquid and an ordered state in the whole Hilbert space by Kondo lattice theory. Even if higher-order multisite terms than the Fock-type term are considered, the ground state cannot be a Mott insulator. It can be merely a gapless semiconductor even if the multisite self-energy is so anomalous that it is divergent at the chemical potential. A Mott insulator is only possible as a high temperature phase.