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Université de Fribourg

Magnetic exchange interactions in Mn doped ZnSnAs₂ chalcopyrite

Bouhani-Benziane, H. ; Sahnoun, Omar ; Sahnoun, Mohammed ; Driz, Mohamed ; Daul, Claude A.

In: Journal of Magnetism and Magnetic Materials, 2015, vol. 396, p. 345–349

Accurate ab initio full-potential augmented plane wave (FP-LAPW) electronic calculations within generalized gradient approximation have been performed for Mn doped ZnSnAs₂ chalcopyrites, focusing on their electronic and magnetic properties as a function of the geometry related to low Mn-impurity concentration and the spin magnetic alignment (i.e., ferromagnetic vs antiferromagnetic). As...

Université de Fribourg

Ab initio study of structural, electronic and thermodynamic properties of tungstate double perovskites Ba₂MWO₆ (M = Mg, Ni, Zn)

Sahnoun, Omar ; Bouhani-Benziane, H. ; Sahnoun, Mohammed ; Driz, Mohamed ; Daul, Claude A.

In: Computational Materials Science, 2013, vol. 77, p. 316–321

The structural and electronic properties of the double perovskite Ba₂MWO₆ with M = Mg, Ni, Zn have been studied using the full-potential linearized augmented plane wave (FP-LAPW) method by employing both the local density approximation (LDA) and the generalized gradient approximation (GGA), which are based on exchange–correlation energy optimization to calculate the total energy. Also we...

Université de Fribourg

Jahn–Teller instability in cationic boron and carbon buckyballs B₈₀⁺ and C₆₀⁺: a comparative study

Muya, Jules Tshishimbi ; Ramanantoanina, Harry ; Daul, Claude A. ; Nguyen, Minh Tho ; Gopakumar, G. ; Ceulemans, Arnout

In: Physical Chemistry Chemical Physics, 2013, vol. 15, no. 8, p. 2829-2835

This paper investigates the Jahn–Teller effect in the icosahedral cation B₈₀⁺ and compares the descent in symmetry with that in C₆₀⁺. For both cations the icosahedral ground state is a ²Hu state, which exhibits a H ⊗ (g ⊕ 2h) Jahn–Teller instability. A detailed construction of the potential energy surface of B₈₀⁺ using different DFT methods including...

Université de Fribourg

General treatment of the multimode Jahn–Teller effect: study of fullerene cations

Ramanantoanina, Harry ; Zlatar, Matija ; García-Fernández, Pablo ; Daul, Claude A. ; Gruden-Pavlović, Maja

In: Physical Chemistry Chemical Physics, 2013, vol. 15, no. 4, p. 1252-1259

A general model for the analysis of the Adiabatic Potential Energy Surfaces (APES) of the molecules that are subject to the multimode Jahn–Teller effect is presented. The method utilizes the information obtained by DFT calculations on a distorted stationary point on the APES. The essence of the model is to express the distortion along a model minimal energy path called Intrinsic Distortion Path...

Université de Fribourg

Density functional theory study of the multimode Jahn-Teller effect – ground state distortion of benzene cation

Zlatar, Matija ; Brog, Jean-Pierre ; Tschannen, Alain ; Gruden-Pavlović, Maja ; Daul, Claude A.

In: Progress in Theoretical Chemistry and Physics, 2012, vol. 23, p. 25-38

The multideterminental-DFT approach performed to analyze Jahn-Teller (JT) active molecules is described. Extension of this method for the analysis of the adiabatic potential energy surfaces and the multimode JT effect is presented. Conceptually a simple model, based on the analogy between the JT distortion and reaction coordinates gives further information about microscopic origin of the JT...

Université de Fribourg

Density functional theory study of the multimode Jahn-Teller problem in the fullerene anion

Ramanantoanina, Harry ; Gruden-Pavlović, Maja ; Zlatar, Matija ; Daul, Claude A.

In: International Journal of Quantum Chemistry, 2012, p. -

The fullerene anion, C₆₀⁻, within the Ih point group, is a spherical molecule subject to the T ⊗ h Jahn–Teller (JT) distortion. The descent in symmetry goes to the three epikernel subgroups, namely D5d, D3d, and D2h. The last one completely removes the electronic...

Université de Fribourg

Electronic fine structure calculation of [Gd(DOTA)(H₂O)]⁻ using LF-DFT: The zero field splitting

Senn, Florian ; Helm, Lothar ; Borel, Alain ; Daul, Claude A.

In: Comptes Rendus Chimie, 2011, vol. 15, no. 2-3, p. 250-254

Zerfo field splitting plays an important role in determining the electron spin relaxation of Gd(III) in solution. We understand the ZFS as an effect depending on the f electron structure and treat it in the framework of ligand field-density functional theory (LF-DFT). We apply this theory to calculate the ZFS of [Gd(DOTA)(H₂O)]⁻ from first principles, having an insight concerning the...

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

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...