A5050282598- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Machine Learning in Materials Science
- Quantum, superfluid, helium dynamics
- Advanced Banach Space Theory
- Optimization and Variational Analysis
- Photochemistry and Electron Transfer Studies
- Advanced NMR Techniques and Applications
- Nonlinear Differential Equations Analysis
- Atomic and Molecular Physics
- Quantum and electron transport phenomena
- Molecular Junctions and Nanostructures
- Quantum Computing Algorithms and Architecture
- Magnetism in coordination complexes
- Electron Spin Resonance Studies
- Image and Signal Denoising Methods
- Physics of Superconductivity and Magnetism
- Quantum many-body systems
- Quantum Information and Cryptography
- X-ray Diffraction in Crystallography
- Spectroscopy and Laser Applications
- Molecular Spectroscopy and Structure
- Fixed Point Theorems Analysis
- Advanced Data Storage Technologies
- Advanced Optimization Algorithms Research
Centre National de la Recherche Scientifique
2014-2024
Laboratoire de Chimie Théorique
2018-2024
Laboratoire de Chimie et Physique Quantiques
2013-2024
Sorbonne Université
2018-2024
Li Creative Technologies (United States)
2022-2023
Laboratoire de Chimie
2019
University of Ferrara
2015-2017
Université Toulouse III - Paul Sabatier
1998-2017
Max Planck Institute for Solid State Research
2017
Université de Toulouse
2013-2016
Defining accurate and compact trial wavefunctions leading to small statistical fixed-node errors in quantum Monte Carlo (QMC) calculations is still a challenging problem. Here we propose make use of selected configuration interaction (CI) expansions obtained by selecting the most important determinants through perturbative criterion. A major advantage with respect truncated CASSCF or CI limited maximum number excitations (e.g, CISD) that much smaller can be considered (many unessential are...
Quantum chemistry is a discipline which relies heavily on very expensive numerical computations. The scaling of correlated wave function methods lies, in their standard implementation, between O(N5) and O(eN) , where N proportional to the system size. Therefore, performing accurate calculations chemically meaningful systems requires (i) approximations that can lower computational (ii) efficient implementations take advantage modern massively parallel architectures. Package an open-source...
Selected configuration interaction (sCI) methods including second-order perturbative corrections provide near full CI (FCI) quality energies with only a small fraction of the determinants FCI space. Here, we introduce both state-specific and multi-state sCI method based on using selection made iteratively (CIPSI) algorithm. The present revises reference (internal) space under effect its outer via construction an effective Hamiltonian, following shifted-Bk philosophy Davidson co-workers. In...
The potential energy curve of the F$_2$ molecule is calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC) using Configuration Interaction (CI)-type trial wavefunctions. To keep number determinants reasonable (the first and second derivatives wavefunction need to be at each step FN-DMC), CI expansion restricted those that contribute most total energy. selection made so-called CIPSI approach (Configuration a Perturbative Selection Iteratively). Quite remarkably, nodes wavefunctions are...
Abstract ADAPT-VQE is a robust algorithm for hybrid quantum-classical simulations of quantum chemical systems on near-term computers. While its iterative process systematically reaches the ground state energy, practical implementations are sensitive to local energy minima, leading over-parameterized ansätze. We introduce Overlap-ADAPT-VQE grow wave-functions by maximizing their overlap with any intermediate target wave-function that already captures some electronic correlation. By avoiding...
This work reports an efficient density-fitting implementation of the density-based basis-set correction (DBBSC) method in MOLPRO software. consists correcting energy calculated by a wave-function with given basis set adapted density functional incorporating short-range electron correlation effects missing set, resulting accelerated convergence to complete-basis-set limit. Different density-functional approximations are explored and complementary-auxiliary-basis-set single-excitation is...
Quantum Computing allows, in principle, the encoding of exponentially scaling many-electron wave function onto a linearly qubit register, offering promising solution to overcome limitations traditional quantum chemistry methods. An essential requirement for ground state algorithms be practical is initialisation qubits high-quality approximation sought-after state. State Preparation (QSP) allows preparation approximate eigenstates obtained from classical calculations, but it frequently...
All-electron Fixed-node Diffusion Monte Carlo calculations for the nonrelativistic ground-state energy of water molecule at equilibrium geometry are presented. The determinantal part trial wavefunction is obtained from a selected Configuration Interaction calculation [Configuration using Perturbative Selection done Iteratively (CIPSI) method] including up to about 1.4 × 106 determinants. Calculations made cc-pCVnZ family basis sets, with n = 2 5. In contrast most quantum works no...
We present a comparative study of the spatial distribution spin density ground state CuCl2 using Density Functional Theory (DFT), quantum Monte Carlo (QMC), and post-Hartree-Fock wave function theory (WFT). A number studies have shown that an accurate description electronic structure lowest-lying states this molecule is particularly challenging due to interplay between strong dynamical correlation effects in 3d shell delocalization hole over chlorine atoms. More generally, problem...
We report a universal density-based basis-set incompleteness correction that can be applied to any wave function method. This correction, which appropriately vanishes in the complete (CBS) limit, relies on short-range correlation density functionals (with multideterminant reference) from range-separated density-functional theory (RS-DFT) estimate error. Contrary conventional RS-DFT schemes require an ad hoc range-separation parameter μ, key ingredient here is μ(r) automatically adapts...
We introduce an approximation to the short-range correlation energy functional with multideterminantal reference involved in a variant of range-separated density-functional theory. This is local density, density gradient, and on-top pair which locally interpolates between standard Perdew-Burke-Ernzerhof at vanishing range-separation parameter known exact asymptotic expansion large parameter. When combined (selected) configuration-interaction calculations for long-range wave function, this...
By combining extrapolated selected configuration interaction (sCI) energies obtained with the Configuration Interaction using a Perturbative Selection made Iteratively algorithm recently proposed short-range density-functional correction for basis-set incompleteness [E. Giner et al., J. Chem. Phys. 149, 194301 (2018)], we show that one can get chemically accurate vertical and adiabatic excitation with, typically, augmented double-ζ basis sets. We illustrate present approach on various types...
An algorithm to compute efficiently the first two derivatives of (very) large multideterminant wavefunctions for quantum Monte Carlo calculations is presented. The calculation determinants and their performed using Sherman-Morrison formula updating inverse Slater matrix. improved implementation based on reduction number column substitutions a very efficient scalar products involved It emphasized that expansions contain in general identical spin-specific determinants: typical configuration...
We present accurate nonrelativistic ground-state energies of the transition metal atoms 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) method and including most prominent determinants full configuration interaction expansion are used as trial wavefunctions. Using maximum few tens thousands determinants, fixed-node errors on total DMC found...
The recently developed semistochastic heat-bath configuration interaction (SHCI) method is a systematically improvable selected plus perturbation theory capable of giving essentially exact energies for larger systems than possible with other such methods. We compute SHCI atomization 55 molecules that have been used as test set in prior studies because their are known from experiment. Basis sets cc-pVDZ to cc-pV5Z used, totaling up 500 orbitals and Hilbert space 1032 Slater determinants the...
We extend to strongly correlated molecular systems the recently introduced basis-set incompleteness correction based on density-functional theory (DFT) [E. Giner et al., J. Chem. Phys. 149, 194301 (2018)]. This relies a mapping between wave-function calculations in finite basis set and range-separated DFT (RSDFT) through definition of an effective non-divergent interaction corresponding electron-electron Coulomb projected set. enables use RSDFT-type complementary density functionals recover...
The basis-set correction method based on density-functional theory consists in correcting the energy calculated by a wave-function with given basis set density functional. This functional incorporates short-range electron correlation effects missing set. results accelerated convergences of ground-state energies to complete-basis-set limit. In this work, we extend linear-response formalism for calculating excited-state energies. We give general equations as well more specific...
The present work proposes to use density-functional theory (DFT) correct for the basis-set error of wave-function (WFT). One key ideas developed here is define a range-separation parameter which automatically adapts given basis set. derivation exact equations are based on Levy-Lieb formulation DFT, helps us complementary functional corrects uniquely WFT. coupling DFT and WFT done through definition real-space representation electron-electron Coulomb operator projected one-particle Such an...
We explore the use in quantum Monte Carlo (QMC) of trial wave functions consisting a Jastrow factor multiplied by truncated configuration-interaction (CI) expansion Slater determinants obtained from CI perturbatively selected iteratively (CIPSI) calculation. In CIPSI algorithm, is enlarged selecting best using perturbation theory, which provides an optimal and automatic way constructing expansions approaching full limit. perform systematic study variational (VMC) fixed-node diffusion (DMC)...
Similar to other electron correlation methods, many-body perturbation theory methods based on Green's functions, such as the so-called GW approximation, suffer from usual slow convergence of energetic properties with respect size one-electron basis set. This displeasing feature is due lack explicit electron-electron terms modeling infamous Kato cusp and Coulomb hole around it. Here, we propose a computationally efficient density-based basis-set correction short-range density functionals...
In this work, we present an extension of popular selected configuration interaction (SCI) algorithms to the Transcorrelated (TC) framework. Although used in work recently introduced one-parameter correlation factor [E. Giner, J. Chem. Phys. 154, 084119 (2021)], theory presented here is valid for any factor. Thanks formalization non-Hermitian TC eigenvalue problem as a search stationary points specific functional depending on both left- and right-functions, obtain general framework, allowing...
The present work introduces a new form of explicitly correlated factor in the context transcorrelated methods. correlation is obtained from r12 ≈ 0 mathematical analysis Hamiltonian, and its analytical such that leading order 1/r12 scalar part effective two-electron potential reproduces long-range interaction range-separated density functional theory. resulting exactly imposes cusp tuned by unique parameter μ, which controls both depth coulomb hole typical range r12. Hamiltonian with has...
In this work, we investigate the performance of a recently proposed transcorrelated (TC) approach based on single-parameter correlation factor [E. Giner, J. Chem. Phys. 154, 084119 (2021)] for systems involving more than two electrons. The benefit such an relies its simplicity as efficient numerical-analytical schemes can be set up to compute two- and three-body integrals occurring in effective TC Hamiltonian. To obtain accurate ground state energies within given basis set, present scheme is...
We introduce a novel three-body correlation factor that is designed to vanish in the core region around each nucleus and approach universal two-body for valence electrons. The transcorrelated Hamiltonian used optimize orbitals of single Slater determinant within biorthonormal framework. Slater–Jastrow wave function optimized on set atomic molecular systems containing both second-row elements 3d transition metal elements. optimization orbitals, along with an increase basis set, results...