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We present the multi-channel Dyson equation that combines two or more many-body Green's functions to describe the electronic structure of materials. In this thesis, we use it to model photoemission spectra by coupling the one-body Green's function with the three-body Green's function and to model neutral excitation by coupling the two-body Green's function with the four-body Green's function . We demonstrate that, unlike methods using only the one-body Green's function, our approach puts the description of quasiparticles and satellites on an equal footing. We propose a multi-channel self-energy that is static and only contains the bare Coulomb interaction, making frequency convolutions and self-consistency unnecessary. Despite its simplicity, we demonstrate with a diagrammatic analysis that the physics it describes is extremely rich. Finally, we present a framework based on an effective Hamiltonian that can be solved for any many-body system using standard numerical tools. We illustrate our approach by applying it to the Hubbard dimer and show that it is exact both at 1/4 and 1/2 filling.

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We present the second release of the real-time time-dependent density functional theory code “Quantum Dissipative Dynamics” (QDD). It augments the first version [1] by a parallelization on a GPU coded with CUDA fortran. The extension focuses on the dynamical part only because this is the most time consuming part when applying the QDD code. The performance of the new GPU implementation as compared to OpenMP parallelization has been tested and checked on a couple of small sodium clusters and small covalent molecules. OpenMP parallelization allows a speed-up by one order of magnitude in average, as compared to a sequential computation. The use of a GPU permits a gain of an additional order of magnitude. The performance gain outweighs even the larger energy consumption of a GPU. The impressive speed-up opens the door for more demanding applications, not affordable before

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We present the multi-channel Dyson equation that combines two or more many-body Green's functions to describe the electronic structure of materials. In this work we use it to model photoemission spectra by coupling the one-body Green's function with the three-body Green's function. We demonstrate that, unlike methods using only the one-body Green's function, our approach puts the description of quasiparticles and satellites on an equal footing. We propose a multi-channel self-energy that is static and only contains the bare Coulomb interaction, making frequency convolutions and self-consistency unnecessary. Despite its simplicity, we demonstrate with a diagrammatic analysis that the physics it describes is extremely rich. Finally, we present a framework based on an effective Hamiltonian that can be solved for any many-body system using standard numerical tools. We illustrate our approach by applying it to the Hubbard dimer and show that it is exact both at 1/4 and 1/2 filling.

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We derive the explicit expression of the three self-energies that one encounters in many-body perturbation theory: the well-known $GW$ self-energy, as well as the particle-particle and electron-hole $T$-matrix self-energies. Each of these can be easily computed via the eigenvalues and eigenvectors of a different random-phase approximation (RPA) linear eigenvalue problem that completely defines their corresponding response function. For illustrative and comparative purposes, we report the principal ionization potentials of a set of small molecules computed at each level of theory.

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Subjets

Damping Molecules Molecular dynamics Propriétés électroniques d'agrégats de sodium et de carbone 3640Cg Collisional time-dependent Hartree-Fock Dynamique moléculaire Matel clusters Molecular irradiation Photo-Electron Spectrum Propriétés électroniques d'agrégats métalliques et de molécules organiques Landau damping RDMFT Fonction de Green Activation neutronique MBPT FOS Physical sciences Hierarchical model Coulomb explosion Hubbard model Interactions de photons avec des systèmes libres Optical response Laser Modèle de Hubbard Deposition dynamics Electron-surface collision Diffusion Radiations Plasmon Hierarchical method Neutron Induced Activation Fission Nucléaire Corrélations Embedded metal cluster Nuclear Electronic properties of metal clusters and organic molecules Monte-Carlo Correction d'auto-interaction Electric field Lasers intenses Corrélations dynamiques Phénomènes dépendant du temps processus d'excitation et de relaxation TDDFT Energy spectrum Dissipative effects Deposition 3115ee Density-functional theory Aggregates R2S Electron emission Mean-field Champ-moyen High intensity lasers Electron correlation Extended time-dependent Hartree-Fock Density Functional Theory Plasmon resonance Pump-and-probe Green's function CAO Photon interactions with free systems Ionization mechanisms Semiclassic Matrice densité Electronic properties of sodium and carbon clusters Coulomb presssure Electronic excitation Photo-electron distributions Time-dependent density-functional theory Metal clusters Dissipation Au-delà du champ moyen Explosion coulombienne Angle-resolved photoelectron spectroscopy Environment Inverse bremsstrahlung collisions Instabilité Neutronique Ar environment Théorie de la fonctionnelle de la densité Collision frequency Dynamics Agregats Irradiation moléculaire Instability Relaxation Méchanismes d'ionisation Atom laser Metal cluster Clusters Electronic emission Chaos 3620Kd Agrégats Numbers 3360+q Nanoplasma Effets dissipatifs Neutronic

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