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Université de Fribourg

Wavelet investigation of La0.5Ca0.5CoO3−δ x-ray absorption data

Sahnoun, Mohammed ; Daul, Claude A. ; Haas, O.

In: Journal of Applied Physics, 2007, vol. 101, no. 1, p. 014911

Morlet wavelet transformation was used to analyze the Co K-edge extended x- ray absorption spectrum of La0.5Ca0.5CoO3−δ. Due to recent success in wavelet analysis of extended x-ray absorption fine structure (EXAFS) data we hoped that the Co–La scattering path could be separated from the Co–Ca scattering path in the EXAFS spectrum of...

Université de Fribourg

Treatment of the multimode Jahn–Teller problem in small aromatic radicals

Gruden-Pavlović, Maja ; Garcia-Fernandez, Pablo ; Andjelkovic, Ljubica ; Daul, Claude A. ; Zlatar, Matija

In: The Journal of Physical Chemistry A, 2012, vol. 115, no. 39, p. 10801–10813

The family of the Jahn–Teller (JT) active hydrocarbon rings, CnHn (n = 5–7), was analyzed by the means of multideterminantal density functional theory (DFT) approach. The multimode problem was addressed using the intrinsic distortion path (IDP) method, in which the JT distortion is expressed as a linear combination of all totally symmetric normal...

Université de Fribourg

Theoretical studies on the electronic properties and the chemical bonding of transition metal complexes using dft and ligand field theory

Atanasov, Mihail ; Daul, Claude A.

In: Chimia, 2005, vol. 59, no. 7-8, p. 504-510

The research activity within our laboratory of computational chemistry at the University of Fribourg is presented. In this review, a brief outline of a recently proposed Ligand Field Density Functional Theory (LFDFT) model for single nuclear and its extension to dimer transition metal complexes is given. Applications of the model to dinuclear complexes are illustrated for the interpretation...

Université de Fribourg

Theoretical modelling of photoactive molecular systems: insights using the Density Functional Theory

Ciofini, Ilaria ; Lainé, Philippe P. ; Bedioui, Fethi ; Daul, Claude A. ; Adamo, Carlo

In: Comptes Rendus Chimie, 2006, vol. 9, no. 2, p. 226-239

Nous rendons compte ici des performances d'une approche moderne et opérante de la théorie de la fonctionnelle de la densité (DFT) pour la prédiction du comportement photophysique de composés du ruthénium (II) et de l'osmium(II). Pour interpréter leurs propriétés d'absorption électronique, l'approche DFT dépendante du temps a été utilisée. Nous illustrons notre propos par l'analyse...

Université de Fribourg

A theoretical characterization of covalency in rare earth complexes through their absorption electronic properties: f-f transitions

Petit, Laurence ; Borel, Alain ; Daul, Claude A. ; Maldivi, Pascale ; Adamo, Carlo

In: Inorganic Chemistry, 2006, vol. 45, no. 18, p. 7382 -7388

Experimental uncertainties concerning the coordination mode of trivalent plutonium in concentrated LiCl have led us to theoretically evaluate the f-f transitions of a series of rare earth aquo and chloro complexes. The calculation of Pr(III), U(III), Np(III), and Pu(III) systems' spectra was undertaken using the LFDFT (ligand field density functional theory) route that combines the backgrounds of...

Université de Fribourg

Structural and electronic properties of isostructural transition metal nitrides

Sahnoun, Mohammed ; Parlebas, J.C. ; Driz, Mohamed ; Daul, Claude A.

In: Physica B: Condensed Matter, 2010, no. 18, p. 3822-3825

The structural and electronic properties of three isostructural transition metal nitrides VN, NbN and TaN have been calculated using the full-potential linearized augmented plane-wave method within a generalized gradient approximation scheme for the exchange-correlation potential. Perfect NaCl structures as well as lattices containing nitrogen vacancies (M₄N₃), and an hexagonal ε-M₂N...

Université de Fribourg

Spectroscopic, structural and DFT study of the responses of carbonylmetal crown ether complexes to alkali metal cations

Stephenson, G. Richard ; Anson, Christopher E. ; Creaser, Colin S. ; Daul, Claude A.

In: European Journal of Inorganic Chemistry, 2011, p. 2086–2097

FTIR spectra of tricarbonyl(η⁶-benzo-15-crown-5)chromium(0) (1) in the presence of lithium, sodium and potassium perchlorate salts in methanol show different responses in the Cr–CO vibrational region of the spectrum. Data from the symmetric (νsym) and antisymmetric (νasym) Cr–CO vibrational stretching modes have been analysed by principal component analysis...