245 citations · 846 across the 27 of their papers we have counts for
26 papers · 1 filter
Non-interacting two-impurity Anderson model on a lattice at particle-hole symmetry
Zakaria M. M. Mahmoud, Jörg Bünemann, Florian Gebhard
We study the non-interacting two-impurity Anderson model on a lattice using the Green function equation-of-motion method. A case of particular interest is the RKKY limit that is ch…
Coulomb matrix elements in multi-orbital Hubbard models
Jörg Bünemann, Florian Gebhard
Coulomb matrix elements are needed in all studies in solid-state theory that are based on Hubbard-type multi-orbital models. Due to symmetries, the matrix elements are not independ…
Exchange couplings for Mn ions in CdTe: validity of spin models for dilute magnetic II-VI semiconductors
Thorben Linneweber, Jörg Bünemann, Ute Löw +2
We employ density-functional theory (DFT) in the generalized gradient approximation (GGA) and its extensions GGA+ and GGA+Gutzwiller to calculate the magnetic exchange couplings…
Approximation schemes for the study of multi-band Gutzwiller wave functions
Jörg Bünemann, Thorben Linneweber, Florian Gebhard
The minimum of the Gutzwiller energy functional depends on the number of parameters considered in the variational state. For a three-orbital Hubbard model we find that the frequent…
Interplay of Coulomb interaction and spin-orbit coupling
Jörg Bünemann, Thorben Linneweber, Ute Löw +2
We employ the Gutzwiller variational approach to investigate the interplay of Coulomb interaction and spin-orbit coupling in a three-orbital Hubbard model. Already in the paramagne…
Evaluation techniques for Gutzwiller wave functions in finite dimensions
Jan Kaczmarczyk, Tobias Schickling, Jörg Bünemann
We give a comprehensive introduction into a diagrammatic method that allows for the evaluation of Gutzwiller wave functions in finite spatial dimensions. We discuss in detail some…
Gutzwiller Density Functional Theory: a formal derivation and application to ferromagnetic nickel
Tobias Schickling, Jörg Bünemann, Florian Gebhard +1
We present a detailed derivation of the Gutzwiller Density Functional Theory that covers all conceivable cases of symmetries and Gutzwiller wave functions. The method is used in a…
High temperature superconductivity in the two-dimensional - model: Gutzwiller wave function solution
J. Kaczmarczyk, J. Bünemann, J. Spałek
A systematic diagrammatic expansion for Gutzwiller-wave functions (DE-GWF) proposed very recently is used for the description of superconducting (SC) ground state in the two-dimens…
Exact response functions within the time-dependent Gutzwiller approach
J. Bünemann, S. Wasner, E. v. Oelsen +1
We investigate the applicability of the two existing versions of a time-dependent Gutzwiller approximation (TDGA) beyond the frequently used limit of infinite spatial dimensions. T…
Linear-Response Dynamics from the Time-Dependent Gutzwiller Approximation
J. Bünemann, M. Capone, J. Lorenzana +1
Within a Lagrangian formalism we derive the time-dependent Gutzwiller approximation for general multi-band Hubbard models. Our approach explicitly incorporates the coupling between…
High-temperature superconductivity in the Hubbard model: Gutzwiller wave-function solution
J. Kaczmarczyk, J. Spałek, T. Schickling +1
A systematic diagrammatic expansion for Gutzwiller-wave functions (DE-GWF) is formulated and used for the description of superconducting (SC) ground state in the two-dimensional Hu…
Numerical minimisation of Gutzwiller energy functionals
Jörg Bünemann, Florian Gebhard, Tobias Schickling +1
We give a comprehensive introduction into an efficient numerical scheme for the minimisation of Gutzwiller energy functionals in studies on multi-band Hubbard models. Our method co…
Gutzwiller theory of band magnetism in LaOFeAs
Tobias Schickling, Florian Gebhard, Jörg Bünemann +3
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…
Variational study of Fermi-surface deformations in Hubbard models
Jörg Bünemann, Tobias Schickling, Florian Gebhard
We study the correlation-induced deformation of Fermi surfaces by means of a new diagrammatic method which allows for the analytical evaluation of Gutzwiller wave functions in fini…
Time-Dependent Gutzwiller Theory for Multiband Hubbard Models
E. v. Oelsen, G. Seibold, J. Buenemann
Based on the variational Gutzwiller theory, we present a method for the computation of response functions for multiband Hubbard models with general local Coulomb interactions. The…
The time-dependent Gutzwiller theory for multi-band Hubbard models
E. v. Oelsen, G. Seibold, J. Bünemann
We formulate a multi-band generalisation of the time-dependent Gutzwiller theory. This approach allows for the calculation of general two-particle response functions, which are cru…
Antiferromagnetic order in multi-band Hubbard models for iron-pnictides
Tobias Schickling, Florian Gebhard, Jörg Bünemann
We investigate multi-band Hubbard models for the three iron 3- bands and the two iron 3- bands in by means of the Gutzwiller variational theor…
Renormalization of Bulk Magnetic Electron States at High Binding Energies
A. Hofmann, X. Y. Cui, J. Schaefer +11
The quasiparticle dynamics of electrons in a magnetically ordered state is investigated by high-resolution angle-resolved photoemission of Ni(110) at 10 K. The self-energy is extra…
Spin-orbit coupling in ferromagnetic Nickel
J. Bünemann, F. Gebhard, T. Ohm +2
We use the Gutzwiller variational theory to investigate the electronic and the magnetic properties of fcc-Nickel. Our particular focus is on the effects of the spin-orbit coupling.…
Orbital order in degenerate Hubbard models : A variational study
Joerg Buenemann, Katalin Javorne-Radnoczi, Patrik Fazekas +1
We use the Gutzwiller variational many-body theory to investigate the stability of orbitally ordered states in a two-band Hubbard-model without spin degrees of freedom. Our results…
Gutzwiller variational theory for the Hubbard model with attractive interaction
Joerg Buenemann, Florian Gebhard, Katalin Radnoczi +1
We investigate the electronic and superconducting properties of a negative-U Hubbard model. For this purpose we evaluate a recently introduced variational theory based on Gutzwille…
Gutzwiller-Correlated Wave Functions: Application to Ferromagnetic Nickel
Joerg Buenemann, Florian Gebhard, Torsten Ohm +2
Ferromagnetic Nickel is the most celebrated iron group metal with pronounced discrepancies between the experimental electronic properties and predictions of density functional theo…
Atomic correlations in itinerant ferromagnets: quasi-particle bands of nickel
J. Buenemann, F. Gebhard, T. Ohm +11
We measure the band structure of nickel along various high-symmetry lines of the bulk Brillouin zone with angle-resolved photoelectron spectroscopy. The Gutzwiller theory for a nin…
Landau-Gutzwiller quasi-particles
J. Buenemann, F. Gebhard, R. Thul
We define Landau quasi-particles within the Gutzwiller variational theory, and derive their dispersion relation for general multi-band Hubbard models in the limit of large spatial…