Dilute limit of a strongly-interacting model of spinless fermions and hardcore bosons on the square lattice
Department of Physics, Cornell University, Ithaca, New York 14853-2501, USA
Corresponding author: a email@example.com
Published online: 28 May 2004
In our model, spinless fermions (or hardcore bosons) on a square lattice hop to nearest neighbor sites, and also experience a hard-core repulsion at the nearest neighbor separation. This is the simplest model of correlated electrons and is more tractable for exact diagonalization than the Hubbard model. We study systematically the dilute limit of this model by a combination of analytical and several numerical approaches: the two-particle problem using lattice Green functions and the t-matrix, the few-fermion problem using a modified t-matrix (demonstrating that the interaction energy is well captured by pairwise terms), and for bosons the fitting of the energy as a function of density to Schick's analytical result for dilute hard disks. We present the first systematic study for a strongly-interacting lattice model of the t-matrix, which appears as the central object in older theories of the existence of a two-dimensional Fermi liquid for dilute fermions with strong interactions. For our model, we can (Lanczos) diagonalize the system at all fillings and the system with four particles, thus going far beyond previous diagonalization works on the Hubbard model.
PACS: 71.10.Fd – Lattice fermion models (Hubbard model, etc.) / 71.10.Pm – Fermions in reduced dimensions (anyons, composite fermions, Luttinger liquid, etc.) / 05.30.Jp – Boson systems / 74.20.Mn – Nonconventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004