2008/10/27 by A. Liebsch, H. Ishida, J. Merino +1 · 1 citation
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Atomic orbital #Condensed matter physics #Coulomb #Electron #Fermi surface #Hubbard model #Magnetic and transport properties of perovskites and related materials #Molecular orbital #Molecule #Mott transition #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Superconductivity #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.78.165123
published as Phys. Rev. B 78, 165123 (2008) · 12 pages, 10 figures
arxiv created 2008/10/27 · openalex publication_date 2008/10/28 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The influence of short-range Coulomb correlations on the Mott transition in the single-band Hubbard model at half filling is studied within cellular dynamical mean-field theory for square and triangular lattices. Finite-temperature exact diagonalization is used to investigate correlations within two-, three-, and four-site clusters. Transforming the nonlocal self-energy from a site basis to a molecular-orbital basis, we focus on the interorbital charge transfer between these cluster molecular orbitals in the vicinity of the Mott transition. In all cases studied, the charge transfer is found to be small, indicating weak Coulomb-induced orbital polarization despite sizable level splitting between orbitals. These results demonstrate that all cluster molecular orbitals take part in the Mott transition and that the insulating gap opens simultaneously across the entire Fermi surface. Thus, at half filling we do not find orbital-selective Mott transitions or a combination of band filling and Mott transition in different orbitals. Nevertheless, the approach toward the transition differs greatly between cluster orbitals, giving rise to a pronounced momentum variation along the Fermi surface, in agreement with previous works. The near absence of Coulomb-induced orbital polarization in these clusters differs qualitatively from single-site multiorbital studies of several transition-metal oxides, where the Mott phase exhibits nearly complete orbital polarization as a result of a correlation driven enhancement of the crystal-field splitting. The strong single-particle coupling among cluster orbitals in the single-band case is identified as the source of this difference.