In: Computer Physics Communications, 2020, vol. 257, no. 2020, p. 107484
The nonequilibrium dynamics of correlated many-particle systems is of interest in connection with pump–probe experiments on molecular systems and solids, as well as theoretical investigations of transport properties and relaxation processes. Nonequilibrium Green’s functions are a powerful tool to study interaction effects in quantum many-particle systems out of equilibrium, and to extract...
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In: Nature Communications, 2020, vol. 11, no. 1, p. 4095
Charge excitations across an electronic band gap play an important role in opto- electronics and light harvesting. In contrast to conventional semiconductors, studies of above-band-gap photoexcitations in strongly correlated materials are still in their infancy. Here we reveal the ultrafast dynamics controlled by Hund’s physics in strongly correlated photoexcited NiO. By combining...
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In: Physical Review B, 2020, vol. 101, no. 19, p. 195118
We consider a two-band spinless model describing an excitonic insulator (EI) on the two-dimensional square lattice with anisotropic hopping parameters and electron-phonon (el-ph) coupling, inspired by the EI candidate Ta2NiSe5. We systematically study the nature of the collective excitations in the ordered phase which originates from the interband Coulomb interaction and the el-ph coupling. ...
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In: Physical Review B, 2020, vol. 101, no. 8, p. 085127
We investigate the effect of nonlocal interactions on the photodoped Mott insulating state of the two-dimensional Hubbard model using a nonequilibrium generalization of the dynamical cluster approximation. In particular, we compare the situation where the excitonic states are lying within the continuum of doublon-holon excitations to a setup where the excitons appear within the Mott gap. In...
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In: Physical Review B, 2019, vol. 100, no. 23, p. 235117
We study the dynamics of charge-transfer insulators after a photoexcitation using the three-band Emery model which is relevant for the description of cuprate superconductors. We provide a detailed derivation of the nonequilibrium extension of the multiband GW + EDMFT formalism and the corresponding downfolding procedure. The Peierls construction of the electron-light coupling is generalized...
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In: Physical Review B, 2019, vol. 100, no. 15, p. 155130
We show that the recently proposed cooling-by-doping mechanism allows one to efficiently prepare interesting nonequilibrium states of the Hubbard model. Using nonequilibrium dynamical mean field theory and a particle-hole symmetric setup with dipolar excitations to full and empty bands we produce cold photodoped Mott insulating states with a sharp Drude peak in the optical conductivity, a ...
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In: Physical Review B, 2019, vol. 100, no. 4, p. 041111
We study the dynamics of charge transfer insulators after photoexcitation using the three-band Emery model and a nonequilibrium extension of Hartree-Fock + EDMFT (extended dynamical mean field theory) and GW + EDMFT. While the equilibrium properties are accurately reproduced by the Hartree-Fock treatment of the ligand bands, dynamical correlations are essential for a proper description of the...
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In: physica status solidi (b), 2019, vol. 256, no. 7, p. 1800469
A fast time propagation method for nonequilibrium Green's functions (NEGF) based on the generalized Kadanoff–Baym Ansatz (GKBA) is applied to a lattice system with a symmetry‐broken equilibrium phase, namely an excitonic insulator (EI). The adiabatic preparation of a correlated symmetry‐broken initial state from a Hartree– Fock wave function within GKBA is assessed by comparing with a...
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In: Physical Review B, 2019, vol. 99, no. 4, p. 045118
We study equilibrium and nonequilibrium properties of electron-phonon systems described by the Hubbard-Holstein model using dynamical mean-field theory. In equilibrium, we benchmark the results for impurity solvers based on the one-crossing approximation and slave-rotor approximation against non-perturbative numerical renormalization group reference data. We also examine how well the...
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In: Physical Review Letters, 2017, vol. 119, no. 24, p. 247601
We study the dynamics of excitonic insulators coupled to phonons using the time- dependent mean-field theory. Without phonon couplings, the linear response is given by the damped amplitude oscillations of the order parameter with a frequency equal to the minimum band gap. A phonon coupling to the interband transfer integral induces two types of long-lived collective oscillations of the...
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