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    • Article
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    Quantum Chemical Characterization of the Bonding of N-Heterocyclic Carbenes to Cp2MI Compounds [M = Ce(III), U(III)]

    Gagliardi, Laura, Cramer, Christopher J.
    Inorganic Chemistry, 2006, 45, 23, 9442-9447
    2006
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    Titre: Quantum Chemical Characterization of the Bonding of N-Heterocyclic Carbenes to Cp2MI Compounds [M = Ce(III), U(III)]
    Auteur: Gagliardi, Laura; Cramer, Christopher J.
    Date: 2006
    Description: The binding of N-heterocyclic carbenes to Ce(III) and U(III) compounds is characterized by quantum chemical methods. Density functional methods are in qualitative agreement with experiment that binding to U(III) is more favorable than to Ce(III); after correcting for basis-set superposition error, quantitative agreement with experiment is achieved with a multireference second-order perturbation theory approach accounting for relativistic effects. The small computed (and observed) preference derives from a combination of several small effects, including differences in electronic binding energies, rovibrational partition functions, and solvation free energies. Prospects for ligand modification to improve the differentiation between lanthanides and actinides are discussed on the basis of computational predictions.
    Fait partie de: Inorganic Chemistry, 2006, 45, 23, 9442-9447

    • Plusieurs versions

    Water clusters to nanodrops: a tight-binding density functional study

    Mir, Pere, Cramer, Christopher J.
    Physical Chemistry Chemical Physics, 2013, Vol.15(6), pp.1837-1843 [Revue évaluée par les pairs]

    • Livre
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    Essentials of computational chemistry : theories and models

    Cramer, Christopher J
    Chichester : J. Wiley
    2009
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    Titre: Essentials of computational chemistry : theories and models / Christopher J. Cramer
    Auteur: Cramer, Christopher J
    Edition: 2nd ed., repr. with corr..
    Editeur: Chichester : J. Wiley
    Date: 2009
    Collation: 596 p. : ill.
    Classification: LC QD455.3
    Identifiant: 9780470091821 (pb) (ISBN); 9780470091814 (hb) (ISBN)
    No RERO: R005521834
    Permalien:
    http://data.rero.ch/01-R005521834/html?view=FR_V1

    • Plusieurs versions

    Mechanistic Study of CpCoIII/RhIII-Catalyzed Directed C–H Functionalization with Diazo Compounds

    Qu, Shuanglin, Cramer, Christopher J
    The Journal of Organic Chemistry, 20 January 2017, Vol.82(2), pp.1195-1204 [Revue évaluée par les pairs]

    • Article
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    Theoretical Characterization of End-On and Side-On Peroxide Coordination in Ligated Cu2O2 Models

    Cramer, Christopher J., Kinal, Armagan, Woch, Marta, Piecuch, Piotr, Gagliardi, Laura
    Journal of Physical Chemistry. A, 2006, 110, 40, 11557-11568
    2006
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    Titre: Theoretical Characterization of End-On and Side-On Peroxide Coordination in Ligated Cu2O2 Models
    Auteur: Cramer, Christopher J.; Kinal, Armagan; Woch, Marta; Piecuch, Piotr; Gagliardi, Laura
    Date: 2006
    Description: The relative energetics of μ-η1:η1 (trans end-on) and μ-η2:η2 (side-on) peroxo isomers of Cu2O2 fragments supported by 0, 2, 4, and 6 ammonia ligands have been computed with various density functional, coupled-cluster, and multiconfigurational protocols. There is substantial disagreement between the different levels for most cases, although completely renormalized coupled-cluster methods appear to offer the most reliable predictions. The significant biradical character of the end-on peroxo isomer proves problematic for the density functionals, while the demands on active space size and the need to account for interactions between different states in second-order perturbation theory prove challenging for the multireference treatments. In the latter case, it proved impossible to achieve any convincing convergence.
    Fait partie de: Journal of Physical Chemistry. A, 2006, 110, 40, 11557-11568

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    How useful are vibrational frequencies of isotopomeric O2 fragments for assessing local symmetry? Some simple systems and the vexing case of a galactose oxidase model

    Kinsinger, Christopher R., Gherman, Benjamin F., Gagliardi, Laura, Cramer, Christopher J.
    Journal of Biological Inorganic Chemistry, 2005, 10, 7, 778-789
    2005
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    Titre: How useful are vibrational frequencies of isotopomeric O2 fragments for assessing local symmetry? Some simple systems and the vexing case of a galactose oxidase model
    Auteur: Kinsinger, Christopher R.; Gherman, Benjamin F.; Gagliardi, Laura; Cramer, Christopher J.
    Date: 2005
    Sujet: Copper superoxide - Copper peroxide - Raman spectroscopy - Galactose oxidase - Density functional theory
    Description: The tendency for mixed-isotope O2 fragments to exhibit different stretching frequencies in asymmetric environments is examined with various levels of electronic structure theory for simple peroxides and peroxyl radicals, as well as for a variety of monocopper–O2 complexes. The study of the monocopper species is motivated by their relevance to the active site of galactose oxidase. Extensive theoretical work with an experimental model characterized by Jazdzewski et al. (J. Biol. Inorg. Chem. 8:381–393, 2003) suggests that the failure to observe a splitting between 16O18Oand 18O16O isotopomers cannot be taken as evidence against end-on O2 coordination. Conformational analysis on an energetic basis, however, is complicated by biradical character inherent in all of the copper–O2 singlet structures.
    Fait partie de: Journal of Biological Inorganic Chemistry, 2005, 10, 7, 778-789

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    Theoretical Models on the Cu2O2 Torture Track: Mechanistic Implications for Oxytyrosinase and Small-Molecule Analogues

    Cramer, Christopher J., Woch, Marta, Piecuch, Piotr, Puzzarini, Cristina, Gagliardi, Laura
    Journal of Physical Chemistry. A, 2006, 11, 5, 1991-2004
    2006
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    Titre: Theoretical Models on the Cu2O2 Torture Track: Mechanistic Implications for Oxytyrosinase and Small-Molecule Analogues
    Auteur: Cramer, Christopher J.; Woch, Marta; Piecuch, Piotr; Puzzarini, Cristina; Gagliardi, Laura
    Date: 2006
    Description: Accurately describing the relative energetics of alternative bis(μ-oxo) and μ-η2:η2 peroxo isomers of Cu2O2 cores supported by 0, 2, 4, and 6 ammonia ligands is remarkably challenging for a wide variety of theoretical models, primarily owing to the difficulty of maintaining a balanced description of rapidly changing dynamical and nondynamical electron correlation effects and a varying degree of biradical character along the isomerization coordinate. The completely renormalized coupled-cluster level of theory including triple excitations and extremely efficient pure density functional levels of theory quantitatively agree with one another and also agree qualitatively with experimental results for Cu2O2 cores supported by analogous but larger ligands. Standard coupled-cluster methods, such as CCSD(T), are in most cases considerably less accurate and exhibit poor convergence in predicted relative energies. Hybrid density functionals significantly underestimate the stability of the bis(μ-oxo) form, with the magnitude of the error being directly proportional to the percentage Hartree−Fock exchange in the functional. Single-root CASPT2 multireference second-order perturbation theory, by contrast, significantly overestimates the stability of bis(μ-oxo) isomers. Implications of these results for modeling the mechanism of C−H bond activation by supported Cu2O2 cores, like that found in the active site of oxytyrosinase, are discussed.
    Fait partie de: Journal of Physical Chemistry. A, 2006, 11, 5, 1991-2004

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    The restricted active space followed by second-order perturbation theory method : theory and application to the study of CuO₂ and Cu₂O₂ systems

    Malmqvist, Per Ake, Pierloot, Kristine, Moughal Shahi, Abdul Rehaman, Cramer, Christopher J., Gagliardi, Laura
    Journal of Chemical Physics, 2008, 128, 204109, 10
    2008
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    Titre: The restricted active space followed by second-order perturbation theory method : theory and application to the study of CuO₂ and Cu₂O₂ systems
    Auteur: Malmqvist, Per Ake; Pierloot, Kristine; Moughal Shahi, Abdul Rehaman; Cramer, Christopher J.; Gagliardi, Laura
    Date: 2008
    Description: A multireference second-order perturbation theory using a restricted active space self-consistent field wave function as reference (RASPT2/RASSCF) is described. This model is particularly effective for cases where a chemical system requires a balanced orbital active space that is too large to be addressed by the complete active space self-consistent field model with or without second-order perturbation theory (CASPT2 or CASSCF, respectively). Rather than permitting all possible electronic configurations of the electrons in the active space to appear in the reference wave function, certain orbitals are sequestered into two subspaces that permit a maximum number of occupations or holes, respectively, in any given configuration, thereby reducing the total number of possible configurations. Subsequent second-order perturbation theory captures additional dynamical correlation effects. Applications of the theory to the electronic structure of complexes involved in the activation of molecular oxygen by mono- and binuclear copper complexes are presented. In the mononuclear case, RASPT2 and CASPT2 provide very similar results. In the binuclear cases, however, only RASPT2 proves quantitatively useful, owing to the very large size of the necessary active space.
    Fait partie de: Journal of Chemical Physics, 2008, 128, 204109, 10

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    Theoretical prediction of linear free energy relationships using proton nucleomers

    La Macchia, Giovanni, Gagliardi, Laura, Carlson, Geoffrey S., Jay, Ashley N., Davis, Erik, Cramer, Christopher J.
    Journal of Physical Organic Chemistry, 2008, 21, 2, 136-145
    2008
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    Titre: Theoretical prediction of linear free energy relationships using proton nucleomers
    Auteur: La Macchia, Giovanni; Gagliardi, Laura; Carlson, Geoffrey S.; Jay, Ashley N.; Davis, Erik; Cramer, Christopher J.
    Date: 2008
    Fait partie de: Journal of Physical Organic Chemistry, 2008, 21, 2, 136-145

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    Early Excited State Dynamics of 6-Styryl-Substituted Pyrylium Salts Exhibiting Dual Fluorescence

    Pigliucci, Anatolio, Nikolov, Peter, Moughal Shahi, Abdul Rehaman, Gagliardi, Laura, Cramer, Christopher J., Vauthey, Eric
    Journal of Physical Chemistry. A, 2006, 110, 33, 9988-9994
    2006
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    Titre: Early Excited State Dynamics of 6-Styryl-Substituted Pyrylium Salts Exhibiting Dual Fluorescence
    Auteur: Pigliucci, Anatolio; Nikolov, Peter; Moughal Shahi, Abdul Rehaman; Gagliardi, Laura; Cramer, Christopher J.; Vauthey, Eric
    Date: 2006
    Description: A series of 6-styryl-2,4-diphenylpyrylium salts exhibiting dual fluorescence has been investigated by fluorescence up-conversion in conjunction with quantum chemical calculations. The short-wavelength emission is due to an excited state localized on the pyrylium fragment and the long-wavelength emission arises from a charge-transfer state delocalized over the whole molecule. The two fluorescing states do not exhibit a precursor−successor relationship. The rise time of the short-wavelength fluorescence is smaller than 200 fs, and that of the long-wavelength emission depends on the electron-donating property of the styryl group substituent. The rise is almost prompt with the weaker donors but is slower, wavelength and viscosity dependent with the strongest electron-donating group. A model involving a S2/S1 conical intersection is proposed to account for these observations.
    Fait partie de: Journal of Physical Chemistry. A, 2006, 110, 33, 9988-9994