- Home

[hal-02292638] Evaluating two-electron-repulsion integrals over arbitrary orbitals using zero variance Monte Carlo: Application to full configuration interaction calculations with Slater-type orbitals (21/09/2019)

[...]

[hal-01149053] Prediction of the Fate of Organic Compounds in the Environment From Their Molecular Properties: A Review (20/09/2019)

A comprehensive review of quantitative structure-activity relationships (QSAR) allowing the prediction of the fate of organic compounds in the environment from their molecular properties was done. The considered processes were water dissolution, dissociation, volatilization, retention on soils and sediments (mainly adsorption and desorption), degradation (biotic and abiotic), and absorption by plants. A total of 790 equations involving 686 structural molecular descriptors are reported to estimate 90 environmental parameters related to these processes. A significant number of equations was found for dissociation process (pKa), water dissolution or hydrophobic behavior (especially through the KOW parameter), adsorption to soils and biodegradation. A lack of QSAR was observed to estimate desorption or potential of transfer to water. Among the 686 molecular descriptors, 5 were found to be dominant in the 790 collected equations and the most generic ones: four quantum-chemical descriptors, the energy of the highest occupied molecular orbital (EHOMO) and the energy of the lowest unoccupied molecular orbital (ELUMO), polarizability (α) and dipole moment (μ), and one constitutional descriptor, the molecular weight (MW). Keeping in mind that the combination of descriptors belonging to different categories (constitutional, topological, quantum-chemical…) led to improve QSAR performances, these descriptors should be considered for the development of new QSAR, for further predictions of environmental parameters. This review also allows finding of the relevant QSAR equations to predict the fate of a wide diversity of compounds in the environment.

[hal-02289342] Capturing static and dynamic correlation with $\Delta \text{NO}$-MP2 and $\Delta \text{NO}$-CCSD (21/09/2019)

The $\Delta \text{NO}$ method for static correlation is combined with second-order M{\o}ller-Plesset perturbation theory (MP2) and coupled-cluster singles and doubles (CCSD) to account for dynamic correlation. The MP2 and CCSD expressions are adapted from finite-temperature CCSD, which includes orbital occupancies and vacancies, and expanded orbital summations. Correlation is partitioned with the aid of damping factors incorporated into the MP2 and CCSD residual equations. Potential energy curves for a selection of diatomics are in good agreement with extrapolated full configuration interaction results (exFCI), and on par with conventional multireference approaches.

[hal-02289341] Chemically Accurate Excitation Energies With Small Basis Sets (21/09/2019)

By combining extrapolated selected configuration interaction (sCI) energies obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) algorithm with the recently proposed short-range density-functional correction for basis-set incompleteness [Giner et al.,J. Chem. Phys. 2018, 149, 194301], we show that one can get chemically accurate vertical and adiabatic excitation energies with, typically, augmented double-$\zeta$ basis sets. We illustrate the present approach on various types of excited states (valence, Rydberg, and double excitations) in several small organic molecules (methylene, water, ammonia, carbon dimer and ethylene). The present study clearly evidences that special care has to be taken with very diffuse excited states where the present correction does not catch the radial incompleteness of the one-electron basis set.

[hal-02289337] Cross-Comparisons between Experiment, TD-DFT, CC, and ADC for Transition Energies (21/09/2019)

[...]

[hal-02282079] New study of the line profiles of sodium perturbed by H 2 (21/09/2019)

The opacity of alkali atoms, most importantly of Na and K, plays a crucial role in the atmospheres of brown dwarfs and exoplanets. We present a comprehensive study of Na-H 2 collisional profiles at temperatures from 500 to 3000 K, the temperatures prevailing in the atmosphere of brown dwarfs and Jupiter-mass planets. The relevant H 2 perturber densities reach several 10 19 cm −3 in hot (T eff 1500 K) Jupiter-mass planets and can exceed 10 20 cm −3 for more massive or cooler objects. Accurate pressure-broadened profiles that are valid at high densities of H 2 should be incorporated into spectral models. Unified profiles of sodium perturbed by molecular hydrogen were calculated in the semi-classical approach using up-to-date molecular data. New Na-H 2 collisional profiles and their effects on the synthetic spectra of brown dwarfs and hot Jupiters computed with petitCODE are presented.

[hal-02156152] Line Profiles of the Calcium I Resonance Line in Cool Metal-polluted White Dwarfs (21/09/2019)

Metal-polluted white dwarfs (DZ stars) are characterized by a helium-rich atmosphere contaminated by heavy elements traces originating from accreted rocky planetesimals. As a detailed spectroscopic analysis of those objects can reveal the composition of the accreted debris, there is a great interest in developing accurate DZ atmosphere models. However, the coolest DZ white dwarfs are challenging to model due to the fluidlike density of their atmospheres. Under such extreme conditions, spectral absorption lines are heavily broadened by interactions with neutral helium, and it is no longer justified to use the conventional Lorentzian profiles. In this work, we determine the theoretical profiles of the Ca I resonance line (the most prominent spectral line for the coolest DZ white dwarfs) in the dense atmospheres of cool DZ white dwarfs. To do so, we use a unified theory of collisional line profiles and accurate ab initio potential energies and transition dipole moments for the CaHe molecule. We present the resulting profiles for the full range of temperatures and helium densities relevant for the modeling of cool, metal-polluted white dwarfs (from 3000 to 6000 K and from 10 21 to 10 23 cm −3). We also implement these new profiles in our atmosphere models and show that they lead to improved fits to the Ca I resonance line of the coolest DZ white dwarfs.

[hal-02184636] The Electronic Structure of Graphene Nanoislands: A CAS-SCF and NEVPT2 Study (21/09/2019)

[...]

[hal-02184560] Conical intersection properties unraveled by the position spread tensor (21/09/2019)

[...]

[hal-02157296] Relativistic equation of motion coupled cluster based on four-compoment Hamiltonians (21/09/2019)

[...]

[hal-02156091] Distributed Gaussian orbitals for molecular calculations: application to simple systems (21/09/2019)

[...]

Relativistic corrections Configuration Interaction Quantum Monte Carlo Coupled cluster calculations Chemical Physics 3115vj Chiral halogenomethanes Béryllium Circular dichroism Atomic and molecular structure and dynamics 3115ag Density Functional Theory Abiotic degradation AROMATIC-MOLECULES Density functional theory Carbon Nanotubes Ab initio calculation Correlation and relativity Petascale COMPUTATION DEPENDENT BASIS-SETS Argile Valence bond ENANTIOMERIC MOLECULES Dynamique Moléculaire Car-Parrinello BENZENE MOLECULE Large systems 3115aj Corrélation et relativité Parity violation Contact electron density Ground states Atom Biodegradation 3115ae Aimantation Time-dependent density-functional theory CIPSI Dichroïsme circulaire Cusp Car-Parrinello molecular dynamics Argon 3315Fm Pesticides Metabolites Clustering Molecular modeling Environmental fate Partial least squares ALGORITHM CP Violation Electric and magnetic properties Quantum Chemistry Chemical concepts Coupled cluster theory Acrolein Excited states Range separation Diatomics molecules ELECTROWEAK INTERACTIONS AB-INITIO CALCULATION Atomic data Basis sets ELECTRONIC-STRUCTURE Beyond Standard Model Polarizabilities Dispersion coefficients AB-INITIO Chiral oxorhenium Chiral transition metal complexes Calcul ab initio Analytic gradient 3115vn Determinants Clay mineral Chemical-Bonds Single-core optimization Relativistic quantum chemistry Perturbation theory Electric Dipole Moments 3115am DENSITY-FUNCTIONAL THEORY Diatomic molecules Anderson mechanism 3470+e Coupled Cluster Brown dwarfs Contact density CHEMICAL-SHIFTS Pesticide Configuration interactions Atrazine Coupled cluster BIOMOLECULAR HOMOCHIRALITY Conditions aux limites périodiques 3115bw Chimie quantique CP violation Spin-orbit interactions Atrazine-cations complexes Dispersion forces Wave functions CLUSTERS Parallel speedup Corrélation électronique