Ivan Duchemin
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View article: Optical spectra of small silver clusters with the Bethe-Salpeter formalism: a Reassessment
Optical spectra of small silver clusters with the Bethe-Salpeter formalism: a Reassessment Open
We study the optical absorption spectra of small Ag_n (n=2,4,6,8) clusters using the Bethe-Salpeter equation (BSE) formalism with a Hamiltonian built from GW quasiparticle energies. Calculations are based on an effective core potential inc…
View article: Joint approximate diagonalization approach to quasiparticle self-consistent <i>GW</i> calculations
Joint approximate diagonalization approach to quasiparticle self-consistent <i>GW</i> calculations Open
We introduce an alternative route to quasiparticle self-consistent GW calculations (qsGW) on the basis of a joint approximate diagonalization of the one-body GW Green’s functions G(εnQP) taken at the input quasiparticle energies. Such an a…
View article: Joint Approximate Diagonalization approach to Quasiparticle Self-Consistent $GW$ calculations
Joint Approximate Diagonalization approach to Quasiparticle Self-Consistent $GW$ calculations Open
We introduce an alternative route to quasiparticle self-consistent $GW$ calculations ($\mathrm{qs}GW$) on the basis of a Joint Approximate Diagonalization of the one-body $GW$ Green's functions $G(\varepsilon_n^{QP})$ taken at the input qu…
View article: Polarizable Continuum Models and Green’s Function <i>GW</i> Formalism: On the Dynamics of the Solvent Electrons
Polarizable Continuum Models and Green’s Function <i>GW</i> Formalism: On the Dynamics of the Solvent Electrons Open
The many-body GW formalism, for the calculation of ionization potentials or electronic affinities, relies on the frequency-dependent dielectric function built from the electronic degrees of freedom. Considering the case of water as a solve…
View article: From many-body ab initio to effective excitonic models: a versatile mapping approach including environmental embedding effects
From many-body ab initio to effective excitonic models: a versatile mapping approach including environmental embedding effects Open
We present an original multi-state projective diabatization scheme based on the Green's function formalism that allows the systematic mapping of many-body ab initio calculations onto effective excitonic models. This method inherits the abi…
View article: Static versus dynamically polarizable environments within the many-body <i>GW</i> formalism
Static versus dynamically polarizable environments within the many-body <i>GW</i> formalism Open
Continuum- or discrete-polarizable models for the study of optoelectronic processes in embedded subsystems rely mostly on the restriction of the surrounding electronic dielectric response to its low frequency limit. Such a description hing…
View article: Assessing the accuracy of TD-DFT excited-state geometries through optimal tuning with <i>GW</i> energy levels
Assessing the accuracy of TD-DFT excited-state geometries through optimal tuning with <i>GW</i> energy levels Open
We study the accuracy of excited state (ES) geometries using optimally tuned LC-PBE functionals with tuning based on GW quasiparticle energies. We compare the results obtained with the PBE, PBE0, non-tuned, and tuned LC-PBE functionals wit…
View article: Static versus dynamically polarizable environments within the many-body $\bf{GW}$ formalism
Static versus dynamically polarizable environments within the many-body $\bf{GW}$ formalism Open
Continuum or discrete polarizable models for the study of optoelectronic processes in embedded subsystems rely mostly on the restriction of the surrounding electronic dielectric response to its low frequency limit. Such a description hinge…
View article: On the Role of Charge Transfer Excitations in Non-Fullerene Acceptors for Organic Photovoltaics
On the Role of Charge Transfer Excitations in Non-Fullerene Acceptors for Organic Photovoltaics Open
Through the development of new non-fullerene electron acceptor (NFA) materials, such as Y6 and its molecular derivatives, the power conversion efficiencies of organic photovoltaics (OPVs) have now exceeded 19%. However, despite this rapid …
View article: Real space grids for def2-TZVP/def2-TZVP-RI basis sets resolution of the identity
Real space grids for def2-TZVP/def2-TZVP-RI basis sets resolution of the identity Open
Real space grids (in Bohr) for def2-TZVP/def2-TZVP-RI basis sets resolution of the identity, as per described in the following works: 1) "Separable resolution-of-the-identity with all-electron Gaussian bases: Application to cubic-scaling R…
View article: Real space grids for def2-TZVP/def2-TZVP-RI basis sets resolution of the identity
Real space grids for def2-TZVP/def2-TZVP-RI basis sets resolution of the identity Open
Real space grids (in Bohr) for def2-TZVP/def2-TZVP-RI basis sets resolution of the identity, as per described in the following works: 1) "Separable resolution-of-the-identity with all-electron Gaussian bases: Application to cubic-scaling R…
View article: Many-body <i>GW</i> calculations with very large scale polarizable environments made affordable: A fully <i>ab initio</i> QM/QM approach
Many-body <i>GW</i> calculations with very large scale polarizable environments made affordable: A fully <i>ab initio</i> QM/QM approach Open
We present a many-body GW formalism for quantum subsystems embedded in discrete polarizable environments containing up to several hundred thousand atoms described at a fully ab initio random phase approximation level. Our approach is based…
View article: Computing photoionization spectra in Gaussian basis sets
Computing photoionization spectra in Gaussian basis sets Open
We present a method to compute the photoionization spectra of atoms and molecules in linear-response, time-dependent density functional theory. The electronic orbital variations corresponding to ionized electrons are expanded on a basis se…
View article: Many-body $GW$ calculations with very large scale polarizable environments made affordable: a fully ab initio QM/QM approach
Many-body $GW$ calculations with very large scale polarizable environments made affordable: a fully ab initio QM/QM approach Open
We present a many-body $GW$ formalism for quantum subsystems embedded in discrete polarizable environments containing up to several hundred thousand atoms described at a fully ab initio random phase approximation level. Our approach is bas…
View article: Lagrangian <i>Z</i>-vector approach to Bethe–Salpeter analytic gradients: Assessing approximations
Lagrangian <i>Z</i>-vector approach to Bethe–Salpeter analytic gradients: Assessing approximations Open
We present an implementation of excited-state analytic gradients within the Bethe–Salpeter equation formalism using an adapted Lagrangian Z-vector approach with a cost independent of the number of perturbations. We focus on excited-state e…
View article: Computing photoionization spectra in Gaussian basis sets
Computing photoionization spectra in Gaussian basis sets Open
We present a method to compute the photoionization spectra of atoms and molecules in linear response time-dependent density functional theory. The electronic orbital variations corresponding to ionized electrons are expanded on a basis set…
View article: Exploring Bethe–Salpeter Excited-State Dipoles: The Challenging Case of Increasingly Long Push–Pull Oligomers
Exploring Bethe–Salpeter Excited-State Dipoles: The Challenging Case of Increasingly Long Push–Pull Oligomers Open
The change of molecular dipole moment induced by photon absorption is key to interpret the measured optical spectra. Except for compact molecules, time-dependent density functional theory (TD-DFT) remains the only theory allowing to quickl…
View article: Excited state potential energy surfaces of <i>N</i>-phenylpyrrole upon twisting: reference values and comparison between BSE/<i>GW</i> and TD-DFT
Excited state potential energy surfaces of <i>N</i>-phenylpyrrole upon twisting: reference values and comparison between BSE/<i>GW</i> and TD-DFT Open
The many-body Green’s function Bethe–Salpeter equation formalism provides an accurate evolution upon twisting of the N-PP excited state surfaces with almost no dependency on the starting exchange-correlation functional contrary to TD-DFT.
View article: Excess and excited-state dipole moments of real-life dyes: a comparison between wave-function, BSE/<i>GW</i>, and TD-DFT values
Excess and excited-state dipole moments of real-life dyes: a comparison between wave-function, BSE/<i>GW</i>, and TD-DFT values Open
Bethe–Salpeter equation (BSE) many-body Greens function formalism provides excess dipole moments (Δ μ ) on the same level or slightly better than that of TD-DFT relying on M06-2X and RSH functionals.
View article: Modeling of excited state potential energy surfaces with the Bethe–Salpeter equation formalism: The 4-(dimethylamino)benzonitrile twist
Modeling of excited state potential energy surfaces with the Bethe–Salpeter equation formalism: The 4-(dimethylamino)benzonitrile twist Open
We present a benchmark study of excited state potential energy surfaces (PES) using the many-body Green’s function GW and Bethe–Salpeter equation (BSE) formalisms, coupled cluster methods, as well as Time-Dependent Density Functional Theor…
View article: Efficient extraction of resonant states in systems with defects
Efficient extraction of resonant states in systems with defects Open
We introduce a new numerical method to compute resonances induced by localized defects in crystals. This method solves an integral equation in the defect region to compute analytic continuations of resolvents. Such an approach enables one …
View article: Modeling of the Bandgap Distribution in Bi-Axially Strained Germanium Crossbeam for Laser Applications
Modeling of the Bandgap Distribution in Bi-Axially Strained Germanium Crossbeam for Laser Applications Open
High tensile strained Ge cavities in crossbeam are promising for the development of integrated laser sources on Si. However, the optimization of such cavities remains more challenging than the uniaxial beams. Indeed, the spatial distributi…
View article: Photoluminescent properties of the carbon-dimer defect in hexagonal boron-nitride: A many-body finite-size cluster approach
Photoluminescent properties of the carbon-dimer defect in hexagonal boron-nitride: A many-body finite-size cluster approach Open
We study the carbon dimer defect in a hexagonal boron-nitride monolayer using\nthe GW and Bethe-Salpeter many-body perturbation theories within a finite size\ncluster approach. While quasiparticle energies converge very slowly with system\…
View article: Cubic-Scaling All-Electron <i>GW</i> Calculations with a Separable Density-Fitting Space–Time Approach
Cubic-Scaling All-Electron <i>GW</i> Calculations with a Separable Density-Fitting Space–Time Approach Open
We present an implementation of the GW space-time approach that allows cubic-scaling all-electron calculations with standard Gaussian basis sets without exploiting any localization or sparsity considerations. The independent-electron susce…
View article: The Bethe–Salpeter Equation Formalism: From Physics to Chemistry
The Bethe–Salpeter Equation Formalism: From Physics to Chemistry Open
The Bethe-Salpeter equation (BSE) formalism is steadily asserting itself as a new efficient and accurate tool in the ensemble of computational methods available to chemists in order to predict optical excitations in molecular systems. In p…
View article: Pros and Cons of the Bethe–Salpeter Formalism for Ground-State Energies
Pros and Cons of the Bethe–Salpeter Formalism for Ground-State Energies Open
The combination of the many-body Green's function GW approximation and the Bethe-Salpeter equation (BSE) formalism has shown to be a promising alternative to time-dependent density functional theory (TD-DFT) for computing vertical transiti…
View article: Robust Analytic-Continuation Approach to Many-Body <i>GW</i> Calculations
Robust Analytic-Continuation Approach to Many-Body <i>GW</i> Calculations Open
The\nanalytic continuation of the GW self-energy from the imaginary to the real-energy\naxis is a central difficulty for approaches exploiting the favorable\nproperties of response functions at imaginary frequencies. Within\na scheme mergi…