TY - GEN A1 - Bünemann, Jörg A1 - Gebhard, Florian A1 - Schickling, Tobias A1 - Weber, Werner T1 - Numerical Minimisation of Gutzwiller Energy Functionals T2 - Physica status solidi : B Y1 - 2012 SN - 1521-3951 VL - 249 IS - 6 SP - 1282 EP - 1291 ER - TY - GEN A1 - Schickling, Tobias A1 - Gebhard, Florian A1 - Bünemann, Jörg A1 - Boeri, Lilia A1 - Andersen, Ole Krogh A1 - Weber, Werner T1 - Gutzwiller Theory of Band Magnetism in LaOFeAs T2 - Physical Review Letters Y1 - 2012 SN - 0031-9007 VL - 108 IS - 3 SP - 036406 ER - TY - GEN A1 - Bünemann, Jörg A1 - Schickling, Tobias A1 - Gebhard, Florian T1 - Variational study of Fermi-surface deformations in Hubbard models T2 - Europhysics Letters Y1 - 2012 SN - 1286-4854 VL - 98 IS - 2 SP - 27006 ER - TY - GEN A1 - Oelsen, E. von A1 - Seibold, Götz A1 - Bünemann, Jörg T1 - The time-dependent Gutzwiller theory for multi-band Hubbard models T2 - New Journal of Physics Y1 - 2011 SN - 1367-2630 VL - 13 SP - 113031-01 EP - 113031-42 ER - TY - GEN A1 - Schickling, Tobias A1 - Gebhard, Florian A1 - Bünemann, Jörg T1 - Antiferromagnetic Order in Multiband Hubbard Models for Iron Pnictides Y1 - 2011 ER - TY - GEN A1 - Bünemann, Jörg A1 - Capone, Michael A1 - Lorenzana, José A1 - Seibold, Götz T1 - Linear-response dynamics from the time-dependent Gutzwiller approximation T2 - New Journal of Physics N2 - 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. Y1 - 2013 UR - http://iopscience.iop.org/article/10.1088/1367-2630/15/5/053050 SN - 1367-2630 VL - 15 ER - TY - GEN A1 - Oelsen, E. von A1 - Seibold, Götz A1 - Bünemann, Jörg T1 - Time-Dependent Gutzwiller Theory for Multiband Hubbard Models T2 - Physical Review Letters Y1 - 2011 SN - 1079-7114 VL - 107 IS - 7 SP - 076402-01 EP - 076402-04 ER - TY - GEN A1 - Bünemann, Jörg A1 - Seibold, Götz T1 - Charge and pairing dynamics in the attractive Hubbard model: Mode coupling and the validity of linear-response theory T2 - Physical Review B N2 - 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. KW - Charge density waves KW - Hartree-Fock methods KW - Hubbard model KW - Linear response theory KW - Mean field theory KW - Variational wave functional methods Y1 - 2017 UR - https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.245139 U6 - https://doi.org/10.1103/PhysRevB.96.245139 SN - 2469-9977 SN - 1538-4489 VL - 96 IS - 24 ER -