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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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Sujets

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

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