Related papers: Gutzwiller approximation for paramagnetic ionic Hu…
We study the phase diagram of the ionic Hubbard model (IHM) at half-filling using dynamical mean field theory (DMFT), with two impurity solvers, namely, iterated perturbation theory (IPT) and continuous time quantum Monte Carlo (CTQMC). The…
We investigate the nature of the insulating phases in a bilayer Hubbard model with intralayer coupling $t$ and interlayer coupling $t_{\perp}$ at large interaction strength $U/t$ and half-filling. We consider a dynamical cluster…
Unusual metallic states involving breakdown of the standard Fermi-liquid picture of long-lived quasiparticles in well-defined band states emerge at low temperatures near correlation-driven Mott transitions. Prominent examples are…
We investigate the metal-insulator transition of the one-dimensional SU(N) Hubbard model for repulsive interaction. Using the bosonization approach a Mott transition in the charge sector at half-filling (k_F=\pi/Na_0) is conjectured for N >…
We provide solid evidence for the long-standing presumption that model Hamiltonians with short-range interactions faithfully reproduce the physics of the long-range Coulomb interaction in real materials. For this aim, we address a generic…
We have investigated the antiferromagnetic phase of the 2D, the 3D and the extended Hubbard models on a bipartite cubic lattice by means of the Composite Operator Method within a two-pole approximation. This approach yields a fully…
The ground state of the Hubbard model is studied within the single-site approximation (SSA) and beyond the SSA. Within the SSA, the ground state is a typical Mott insulator at the critical point n=1 and U/W=+infty, with n being the electron…
We study the one-band Hubbard model at half filling with hopping asymmetry and its effective model at finite but large U up to the second order of tmix/U. Two variational wave functions, the resonating valence bond (RVB) wave function and…
We derive an effective Hamiltonian $H_{eff}$ for an ionic Hubbard chain, valid for $t\ll U,\Delta $, where $t$ is the hopping, $U$ the Coulomb repulsion, and $\Delta$ the charge transfer energy. $H_{eff}$ is the minimal model for describing…
We discuss the superfluid to Mott-insulator transition of cold atoms in optical lattices recently observed by Greiner et.al. (Nature 415, 39 (2002)). The fundamental properties of both phases and their experimental signatures are discussed…
We use the Gutzwiller variational theory to calculate the ground-state phase diagram and quasi-particle bands of LaOFeAs. The Fe3d--As4p Wannier-orbital basis obtained from density-functional theory defines the band part of our eight-band…
We investigate the magnetic properties and Mott transition in the Hubbard model for weakly coupled chains on the anisotropic triangular lattice. Taking into account 120$^\circ$ N\'eel, and collinear orderings, the magnetic phase diagram is…
We obtain the quantum phase diagram of the ionic Hubbard model including electron-hole symmetric density-dependent hopping. The boundaries of the phases are determined by crossing of excited levels with particular discrete symmetries, which…
The strong coupling diagram technique is used for investigating states near the metal-insulator transition in the half-filled two-dimensional repulsive Hubbard model. The nonlocal third-order term is included in the irreducible part along…
We present a quantum critical behavior of the renormalized single-particle Wannier function, calculated in the Gutzwiller correlated state near the insulator-metal transition (IMT) for cubic lattices. The wave function size and its maximum,…
Around a metal-to-insulator transition driven by repulsive interaction (Mott transition) the single particle excitations and the collective excitations are equally important. Here we present results for the generic susceptibilities at zero…
We study the physics of a mobile impurity confined in a lattice, moving within a Bose-Hubbard bath at zero temperature. Within the Quantum Gutzwiller formalism, we develop a beyond-Fr\"ohlich model of the bath-impurity interaction. Results…
We study the Mott-insulator transition of bosonic atoms in optical lattices. Using perturbation theory, we analyze the deviations from the mean-field Gutzwiller ansatz, which become appreciable for intermediate values of the ratio between…
Two very different methods -- exact diagonalization on finite chains and a variational method -- are used to study the possibility of a metal-insulator transition in the symmetric half-filled periodic Anderson-Hubbard model. With this aim…
We calculate the density of states in the half-filled Hubbard model on a Bethe lattice with infinite connectivity. Based on our analytical results to second order in $t/U$, we propose a new `Fixed-Energy Exact Diagonalization' scheme for…