@misc{BuenemannGebhardSchicklingetal., author = {B{\"u}nemann, J{\"o}rg and Gebhard, Florian and Schickling, Tobias and Weber, Werner}, title = {Numerical Minimisation of Gutzwiller Energy Functionals}, series = {Physica status solidi : B}, volume = {249}, journal = {Physica status solidi : B}, number = {6}, issn = {1521-3951}, pages = {1282 -- 1291}, language = {en} } @misc{SchicklingGebhardBuenemannetal., author = {Schickling, Tobias and Gebhard, Florian and B{\"u}nemann, J{\"o}rg and Boeri, Lilia and Andersen, Ole Krogh and Weber, Werner}, title = {Gutzwiller Theory of Band Magnetism in LaOFeAs}, series = {Physical Review Letters}, volume = {108}, journal = {Physical Review Letters}, number = {3}, issn = {0031-9007}, pages = {036406}, language = {en} } @misc{BuenemannSchicklingGebhard, author = {B{\"u}nemann, J{\"o}rg and Schickling, Tobias and Gebhard, Florian}, title = {Variational study of Fermi-surface deformations in Hubbard models}, series = {Europhysics Letters}, volume = {98}, journal = {Europhysics Letters}, number = {2}, issn = {1286-4854}, pages = {27006}, language = {en} } @misc{OelsenSeiboldBuenemann, author = {Oelsen, E. von and Seibold, G{\"o}tz and B{\"u}nemann, J{\"o}rg}, title = {The time-dependent Gutzwiller theory for multi-band Hubbard models}, series = {New Journal of Physics}, volume = {13}, journal = {New Journal of Physics}, issn = {1367-2630}, pages = {113031-01 -- 113031-42}, language = {en} } @misc{SchicklingGebhardBuenemann, author = {Schickling, Tobias and Gebhard, Florian and B{\"u}nemann, J{\"o}rg}, title = {Antiferromagnetic Order in Multiband Hubbard Models for Iron Pnictides}, language = {en} } @misc{BuenemannCaponeLorenzanaetal., author = {B{\"u}nemann, J{\"o}rg and Capone, Michael and Lorenzana, Jos{\´e} and Seibold, G{\"o}tz}, title = {Linear-response dynamics from the time-dependent Gutzwiller approximation}, series = {New Journal of Physics}, volume = {15}, journal = {New Journal of Physics}, issn = {1367-2630}, abstract = {Within a Lagrangian formalism, we derive the time-dependent Gutzwiller approximation for general multi-band Hubbard models. Our approach explicitly incorporates the coupling between time-dependent variational parameters and a time-dependent density matrix from which we obtain dynamical correlation functions in the linear-response regime. Our results are illustrated for the one-band model where we show that the interacting system can be mapped to an effective problem of fermionic quasiparticles coupled to 'doublon' (double occupancy) bosonic fluctuations. The latter have an energy on the scale of the on-site Hubbard repulsion U in the dilute limit but become soft at the Brinkman-Rice transition, which is shown to be related to an emerging conservation law of doublon charge and the associated gauge invariance. Coupling with the boson mode produces a structure in the charge response and we find that a similar structure appears in dynamical mean-field theory.}, language = {en} } @misc{OelsenSeiboldBuenemann, author = {Oelsen, E. von and Seibold, G{\"o}tz and B{\"u}nemann, J{\"o}rg}, title = {Time-Dependent Gutzwiller Theory for Multiband Hubbard Models}, series = {Physical Review Letters}, volume = {107}, journal = {Physical Review Letters}, number = {7}, issn = {1079-7114}, pages = {076402-01 -- 076402-04}, language = {en} } @misc{BuenemannSeibold, author = {B{\"u}nemann, J{\"o}rg and Seibold, G{\"o}tz}, title = {Charge and pairing dynamics in the attractive Hubbard model: Mode coupling and the validity of linear-response theory}, series = {Physical Review B}, volume = {96}, journal = {Physical Review B}, number = {24}, issn = {2469-9977}, doi = {10.1103/PhysRevB.96.245139}, abstract = {Pump-probe experiments have turned out as a powerful tool in order to study the dynamics of competing orders in a large variety of materials. The corresponding analysis of the data often relies on standard linear-response theory generalized to nonequilibrium situations. Here we examine the validity of such an approach for the charge and pairing response of systems with charge-density wave and (or) superconducting (SC) order. Our investigations are based on the attractive Hubbard model which we study within the time-dependent Hartree-Fock approximation. In particular, we calculate the quench and pump-probe dynamics for SC and charge order parameters in order to analyze the frequency spectra and the coupling of the probe field to the specific excitations. Our calculations reveal that the "linear-response assumption" is justified for small to moderate nonequilibrium situations (i.e., pump pulses) in the case of a purely charge-ordered ground state. However, the pump-probe dynamics on top of a superconducting ground state is determined by phase and amplitude modes which get coupled far from the equilibrium state indicating the failure of the linear-response assumption.}, language = {en} }