A framework, called time-dependent ghost Gutzwiller approximation (td-gGA), is suited for studying nonequilibrium dynamics in correlated electron systems. By performing benchmark calculations on the Hubbard model, it's demonstrated that td-gGA method captures relaxation of local observables and achieves a quantitative agreement with td-DMFT wide range model parameters timescales.

Mott-Hubbard metal-insulator transitions in N -fold degenerate Hubbard models are studied within the Gutzwiller approximation. For any rational filling with x (integer) electrons per site it is found that metal-insulator transition occurs at a critical correlation energy Uc(N,x) = Uc(N, 2N − x) = γ(N,x)|ǭ(N,x)|, where ǭ is the band energy per particle for the uncorrelated Fermi-liquid state and...

In the present paper we study chemical potential of a generalized Hubbard model with correlated hopping at half-filling using a generalized mean-field approximation. For the special case of the model the approach reproduces the exact results: metalinsulator transition, ground state energy. Chemical potential of generelized Hubbard model with correlated hoppig as function of hopping integrals at...

The dynamical cluster approximation (DCA) is a method which systematically incorporates nonlocal corrections to the dynamical mean-field approximation. Here we present a pedagogical discussion of the DCA by describing it as a ̊-derivable coarse-graining approximation in k-space, which maps an infinite lattice problem onto a periodic finite-sized cluster embedded in a self-consistently determine...

By using the generalized Femi-Dirac distribution in the interpolation approximation [H. Hasegawa, arXiv:0904.2399], we have discussed magnetic and thermodynamical properties of nonextensive itinerant-electron (metallic) ferromagnets described by the Hubbard model combined with the Hartree-Fock approximation. Magnetic moment, energy, specific heat and spin susceptibility are calculated as functi...

We systematically investigate the mode dispersion and spectral weight of the elementary excitation spectra in one-dimensional continuum and lattice electron systems by using the RPA, the Luttinger liquid model, and the Hubbard model. Both charge and spin excitations are studied in detail and compared among the theoretical models. For the lattice Hubbard model we use both Bethe-ansatz equations ...

The last decade has seen a large increase in the number of electronic-structure calculations that involve adding a Hubbard term to the local-density approximation band-structure Hamiltonian. The Hubbard term is then determined either at the mean-field level or with sophisticated many-body techniques such as using dynamical mean-field theory. We review the physics underlying these approaches and...

We present a study of the one-particle spectral properties for a variety of models of Luttinger liquids with open boundaries. We first consider the Tomonaga-Luttinger model using bosonization. For weak interactions the boundary exponent of the power-law suppression of the spectral weight close to the chemical potential is dominated by a term linear in the interaction. This motivates us to study...

We use maximally localized Wannier functions to construct tight-binding (TB) parametrizations for the eg bands of LaMnO3 based on first-principles electronic structure calculations. We compare two different ways to represent the relevant bands around the Fermi level: (i) a d-p model that includes atomic-like orbitals corresponding to both Mn(d) and O(p) states in the TB basis, and (ii) an effec...

The magnetic phase diagrams of models for quasi-one-dimensional compounds belonging to the ironbased-superconductor family are presented. The five-orbital Hubbard model and the real-space Hartree–Fock approximation are employed, supplemented by density functional theory to obtain the hopping amplitudes. Phase diagrams are constructed by varying the Hubbard U and Hund J couplings at zero tempera...