In this perspective,we review the chemical information encoded in electron density and other ingredients used in semilocal functionals.This information is usually looked at from the functional point of view:the exchan...In this perspective,we review the chemical information encoded in electron density and other ingredients used in semilocal functionals.This information is usually looked at from the functional point of view:the exchange density or the enhancement factor are discussed in terms of the reduced density gradient.However,what parts of a molecule do these 3D functions represent? We look atthese quantities in real space,aiming to understand the electronic structure information they encode and provide an insight from the quantum chemical topology(QCT).Generalized gradient approximations(GGAs) provide information about the presence of chemical interactions,whereas meta-GGAs can differentiate between the different bonding types.By merging these two techniques,we show new insight into the failures of semilocal functionals owing to three main errors:fractional charges,fractional spins,and non-covalent interactions.We build on simple models.We also analyze the delocalization error in hydrogen chains,showing the ability of QCT to reveal the delocalization error introduced by semilocal functionals.Then,we show how the analysis of localization can help understand the fractional spin error in alkali atoms,and how it can be used to correct it.Finally,we show that the poor description of GGAs of isodesmic reactions in alkanes is due to 1,3-interactions.展开更多
By the functional B3LYP and M05-2X of DFT and in two bases set, more and more extended (6-311G and 6-311G (d, p)), theoretical study of antioxidant properties of four hydrazones was carried out. The calculations made ...By the functional B3LYP and M05-2X of DFT and in two bases set, more and more extended (6-311G and 6-311G (d, p)), theoretical study of antioxidant properties of four hydrazones was carried out. The calculations made concern the geometrical, spectroscopic and electronic parameters of the molecules. Analysis of the results relating to the geometrical parameters was carried out by calculating interatomic distances, relative errors between calculated values and those obtained experimentally by X-ray diffraction found in the literature. The 13C NMR spectra were calculated by GIAO (Gauge Including Atomic Orbitals) methods, and the results were subjected to statistical analysis by calculating Mean Absolute Deviation (MAD), Root Mean. Square (RMS) and the correlation coefficient (R2), in comparison with experimental spectra. The analysis of the results of calculations of various electronic parameters (hardness (η), softness (S), electronegativity (χ), electrophile index (ω), energy gap (HOMO-LUMO)) reveals that, overall, the methods M05-2X/6-311G (d, p) and B3LYP/6-311G (d, p) found that (R) - (?) - carvone salicylhydrazone (N2) is the most antioxidant molecule of the four molecules and also classify them according to their stability. This confirms the results obtained on the antitrypanosomal activity, the toxicity, the cytotoxicity and the selectivity of the synthesized compounds. ?展开更多
Quantum chemical computations have been performed to evaluate the first and second hyperpolarizability quantities of the interference term, linear in the external static electric field, that appear in the electric fie...Quantum chemical computations have been performed to evaluate the first and second hyperpolarizability quantities of the interference term, linear in the external static electric field, that appear in the electric field-induced sum-frequency generation signal of chiral liquids. These are performed at the time-dependent Hartree-Fock level on the prototypical 1,1′-bi-2-naphtol chiral species.展开更多
Building on the pioneering work of Jean-Marie André and working in the laboratory he founded, the authors have developed a code called FT-1D to make Hartree-Fock electronic structure computations for stereoregula...Building on the pioneering work of Jean-Marie André and working in the laboratory he founded, the authors have developed a code called FT-1D to make Hartree-Fock electronic structure computations for stereoregular polymers using Ewald-type convergence acceleration methods. That code also takes full advantage of all line-group symmetries to calculate only the minimal set of two-electron integrals and to optimize the computation of the Fock matrix. The present communication reports a benchmark study of the FT-1D code using polytetrafluoroethylene(PTFE) as a test case. Our results not only confirm the algorithmic correctness of the code through agreement with other studies where they are applicable, but also show that the use of convergence acceleration enables accurate results to be obtained in situations where other widely-used codes(e.g., PLH and Crystal) fail. It is also found that full attention to the line-group symmetry of the PTFE polymer leads to an increase of between one and two orders of magnitude in the speed of computation. The new code can therefore be viewed as extending the range of electronic-structure computations for stereoregular polymers beyond the present scope of the successful and valuable code Crystal.展开更多
In this paper,we model laser-gas interactions and propagation in some extreme regimes.After a mathematical study of a micro-macro Maxwell-Schrödinger model[1]for short,high-frequency and intense laser-gas interac...In this paper,we model laser-gas interactions and propagation in some extreme regimes.After a mathematical study of a micro-macro Maxwell-Schrödinger model[1]for short,high-frequency and intense laser-gas interactions,we propose to improve this model by adding a plasma equation in order to precisely take into account free electron effects.We examine if such a model can predict and explain complex structures such as filaments,on a physical and numerical basis.In particular,we present in this paper a first numerical observation of nonlinear focusing effects using an ab-initio gas representation and linking our results with existing nonlinear models.展开更多
We analyze the classical penalty algorithm for nonlinear programming in Hilbert spaces and obtain global convergence results, as well as asymptotic superlinear convergence order. These convergence results generalize s...We analyze the classical penalty algorithm for nonlinear programming in Hilbert spaces and obtain global convergence results, as well as asymptotic superlinear convergence order. These convergence results generalize similar results obtained for finite-dimensional problems. Moreover, the nature of the algorithms allows us to solve the unconstrained subproblems in finite-dimensional spaces.展开更多
基金supported partially by the Framework of CALSIMLAB under the Public Grant ANR-11-LABX-0037-01 Overseen by the French National Research Agency(ANR) as Part of the "Investissements d’Avenir" Program(reference:ANR-11-IDEX-0004-02)the National Science Foundation(CHE-1362927)the National Institute of Health(R01-GM061870),USA
文摘In this perspective,we review the chemical information encoded in electron density and other ingredients used in semilocal functionals.This information is usually looked at from the functional point of view:the exchange density or the enhancement factor are discussed in terms of the reduced density gradient.However,what parts of a molecule do these 3D functions represent? We look atthese quantities in real space,aiming to understand the electronic structure information they encode and provide an insight from the quantum chemical topology(QCT).Generalized gradient approximations(GGAs) provide information about the presence of chemical interactions,whereas meta-GGAs can differentiate between the different bonding types.By merging these two techniques,we show new insight into the failures of semilocal functionals owing to three main errors:fractional charges,fractional spins,and non-covalent interactions.We build on simple models.We also analyze the delocalization error in hydrogen chains,showing the ability of QCT to reveal the delocalization error introduced by semilocal functionals.Then,we show how the analysis of localization can help understand the fractional spin error in alkali atoms,and how it can be used to correct it.Finally,we show that the poor description of GGAs of isodesmic reactions in alkanes is due to 1,3-interactions.
文摘By the functional B3LYP and M05-2X of DFT and in two bases set, more and more extended (6-311G and 6-311G (d, p)), theoretical study of antioxidant properties of four hydrazones was carried out. The calculations made concern the geometrical, spectroscopic and electronic parameters of the molecules. Analysis of the results relating to the geometrical parameters was carried out by calculating interatomic distances, relative errors between calculated values and those obtained experimentally by X-ray diffraction found in the literature. The 13C NMR spectra were calculated by GIAO (Gauge Including Atomic Orbitals) methods, and the results were subjected to statistical analysis by calculating Mean Absolute Deviation (MAD), Root Mean. Square (RMS) and the correlation coefficient (R2), in comparison with experimental spectra. The analysis of the results of calculations of various electronic parameters (hardness (η), softness (S), electronegativity (χ), electrophile index (ω), energy gap (HOMO-LUMO)) reveals that, overall, the methods M05-2X/6-311G (d, p) and B3LYP/6-311G (d, p) found that (R) - (?) - carvone salicylhydrazone (N2) is the most antioxidant molecule of the four molecules and also classify them according to their stability. This confirms the results obtained on the antitrypanosomal activity, the toxicity, the cytotoxicity and the selectivity of the synthesized compounds. ?
基金The calculations were performed on the computing facilities of the Consortium deséquipements de Calcul Intensif(CéCI),in particular those of the Plateforme Technologique de Calcul Intensif(PTCI)installed in the University of Namur,for which we gratefully acknowledge financial support of the FNRS-FRFC(2.4.617.07.F,2.5020.11)
文摘Quantum chemical computations have been performed to evaluate the first and second hyperpolarizability quantities of the interference term, linear in the external static electric field, that appear in the electric field-induced sum-frequency generation signal of chiral liquids. These are performed at the time-dependent Hartree-Fock level on the prototypical 1,1′-bi-2-naphtol chiral species.
基金FEH was supported by U.S.National Science Foundation Grant PHY-0601758Part of this research has been funded by BELSPO(IAP P7/05 network"Functional Supramolecular Systems")+1 种基金The calculations were performed on the computing facilities of the Consortium deséquipements de Calcul Intensif(CéCI),in particular those of the Plateforme Technologique de Calcul Intensif(PTCI)installed in the University of Namur,for which we gratefully acknowledge financial support of the FNRS-FRFC(Conventions No.2.4.617.07.F and 2.5020.11)the University of Namur
文摘Building on the pioneering work of Jean-Marie André and working in the laboratory he founded, the authors have developed a code called FT-1D to make Hartree-Fock electronic structure computations for stereoregular polymers using Ewald-type convergence acceleration methods. That code also takes full advantage of all line-group symmetries to calculate only the minimal set of two-electron integrals and to optimize the computation of the Fock matrix. The present communication reports a benchmark study of the FT-1D code using polytetrafluoroethylene(PTFE) as a test case. Our results not only confirm the algorithmic correctness of the code through agreement with other studies where they are applicable, but also show that the use of convergence acceleration enables accurate results to be obtained in situations where other widely-used codes(e.g., PLH and Crystal) fail. It is also found that full attention to the line-group symmetry of the PTFE polymer leads to an increase of between one and two orders of magnitude in the speed of computation. The new code can therefore be viewed as extending the range of electronic-structure computations for stereoregular polymers beyond the present scope of the successful and valuable code Crystal.
文摘In this paper,we model laser-gas interactions and propagation in some extreme regimes.After a mathematical study of a micro-macro Maxwell-Schrödinger model[1]for short,high-frequency and intense laser-gas interactions,we propose to improve this model by adding a plasma equation in order to precisely take into account free electron effects.We examine if such a model can predict and explain complex structures such as filaments,on a physical and numerical basis.In particular,we present in this paper a first numerical observation of nonlinear focusing effects using an ab-initio gas representation and linking our results with existing nonlinear models.
文摘We analyze the classical penalty algorithm for nonlinear programming in Hilbert spaces and obtain global convergence results, as well as asymptotic superlinear convergence order. These convergence results generalize similar results obtained for finite-dimensional problems. Moreover, the nature of the algorithms allows us to solve the unconstrained subproblems in finite-dimensional spaces.