A5053076054- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum, superfluid, helium dynamics
- Quantum and electron transport phenomena
- Molecular Junctions and Nanostructures
- Advanced Physical and Chemical Molecular Interactions
- Photochemistry and Electron Transfer Studies
- Quantum chaos and dynamical systems
- Quantum Dots Synthesis And Properties
- Surface and Thin Film Phenomena
- Perovskite Materials and Applications
- Soil Geostatistics and Mapping
- Machine Learning in Materials Science
- Quantum many-body systems
- Probabilistic and Robust Engineering Design
- Mass Spectrometry Techniques and Applications
- Quantum Mechanics and Non-Hermitian Physics
- Physics of Superconductivity and Magnetism
- Spectral Theory in Mathematical Physics
Laboratoire de Chimie et Physique Quantiques
2021-2025
Université de Toulouse
2021-2025
Centre National de la Recherche Scientifique
2021-2025
Université Toulouse III - Paul Sabatier
2021-2024
University of Oxford
2023
Vrije Universiteit Amsterdam
2022
Upon ionization of an atom or a molecule, another electron (or more) can be simultaneously excited. These concurrently generated states are called "satellites" shakeup transitions) as they appear in spectra higher-energy peaks with weaker intensity and larger width than the main associated single-particle ionizations. Satellites, which correspond to electronically excited cationic species, notoriously challenging model using conventional single-reference methods due their high excitation...
Due to the infinite summation of bubble diagrams, GW approximation Green’s function perturbation theory has proven particularly effective in weak correlation regime, where this family Feynman diagrams is important. However, performance multireference molecular systems, characterized by strong electron correlation, remains relatively unexplored. In present study, we investigate ability handle closed-shell systems their singlet ground state examining four paradigmatic scenarios. First, analyze...
The pair coupled cluster doubles (pCCD) method (where the excitation manifold is restricted to electron pairs) has a series of interesting features. Among others, it provides ground-state energies very close what obtained with doubly occupied configuration interaction (DOCI), but polynomial cost (compared exponential latter). Here, we address whether this similarity holds for excited states by exploring symmetric dissociation linear H
State-specific electronic structure theory provides a route toward balanced excited-state wave functions by exploiting higher-energy stationary points of the energy. Multiconfigurational function approximations can describe both closed- and open-shell excited states avoid issues associated with state-averaged approaches. We investigate existence solutions in complete active space self-consistent field (CASSCF) characterize their topological properties. demonstrate that state-specific provide...
The family of Green's function methods based on the GW approximation has gained popularity in electronic structure theory thanks to its accuracy weakly correlated systems combined with cost-effectiveness. Despite this, self-consistent versions still pose challenges terms convergence. A recent study [Monino and Loos J. Chem. Phys. 2022, 156, 231101.] linked these convergence issues intruder-state problem. In this work, a perturbative analysis similarity renormalization group (SRG) approach is...
Hedin's equations provide an elegant route to compute the exact one-body Green's function (or propagator) via self-consistent iteration of a set non-linear equations. Its first-order approximation, known as $GW$, corresponds resummation ring diagrams and has shown be extremely successful in physics chemistry. Systematic improvement is possible, although challenging, introduction vertex corrections. Considering anomalous propagators external pairing potential, we derive new closed equivalent...
The Bethe-Salpeter equation has been extensively employed to compute the two-body electron-hole propagator and its poles which correspond neutral excitation energies of system. Through a different time-ordering, Green's function can also describe propagation two electrons or holes. corresponding are double ionization potentials electron affinities In this work, for particle-particle is derived within linear-response formalism using pairing field anomalous propagators. This framework allows...
Here, we build on the works of Scuseria et al. [J. Chem. Phys. 129, 231101 (2008)] and Berkelbach 149, 041103 (2018)] to show connections between Bethe–Salpeter equation (BSE) formalism combined with GW approximation from many-body perturbation theory coupled-cluster (CC) at ground- excited-state levels. In particular, how recast equations as non-linear CC-like equations. Similitudes BSE@GW similarity-transformed equation-of-motion CC method are also put forward. The present work allows us...
The cumulant expansion of the Green's function is a computationally efficient beyond-$GW$ approach renowned for its significant enhancement satellite features in materials. In contrast to ubiquitous $GW$ approximation many-body perturbation theory, \textit{ab initio} expansions performed on top ($GW$+C) have demonstrated capability handle multi-particle processes by incorporating higher-order correlation effects or vertex corrections, yielding better agreements between experiment and theory...
Electrons that are delocalized in space because of quantum effects can become localized by an external disordered potential (Anderson localization) or their mutual Coulomb repulsion (Mott/Wigner localization). A simple model addresses what happens when both present, how to quantify the degree localization, and whether approximate methods capture relevant physics.
In single-reference coupled-cluster (CC) methods, one has to solve a set of non-linear polynomial equations in order determine the so-called amplitudes that are then used compute energy and other properties. Although it is common practice converge (lowest-energy) ground-state solution, also possible, thanks tailored algorithms, access higher-energy roots these may or not correspond genuine excited states. Here, we explore structure landscape variational CC compare with its (projected)...
We provide an in-depth examination of the $GW$ approximation Green's function many-body perturbation theory by detailing both its theoretical and practical aspects in realm quantum chemistry. First, quasiparticle context is introduced before delving into derivation Hedin's equations. From these, we explain how to derive well-known self-energy. In a second time, meticulously each step involved calculation what type physical quantities can be computed. To illustrate versatility, consider two...
The family of Green's function methods based on the $GW$ approximation has gained popularity in electronic structure theory thanks to its accuracy weakly correlated systems combined with cost-effectiveness. Despite this, self-consistent versions still pose challenges terms convergence. A recent study \href{https://doi.org/10.1063/5.0089317}{[J. Chem. Phys. 156, 231101 (2022)]} linked these convergence issues intruder-state problem. In this work, a perturbative analysis similarity...