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Université de Fribourg

Exchange energy gradients with respect to atomic positions and cell parameters within the Hartree-Fock Γ-point approximation

Weber, Valéry ; Daul, Claude A. ; Challacombe, Matt

In: The Journal of Chemical Physics, 2006, vol. 124, p. 214105

Recently, linear scaling construction of the periodic exact Hartree-Fock exchange matrix within the Γ-point approximation has been introduced [J. Chem. Phys. 122, 124105 (2005)]. In this article, a formalism for evaluation of analytical Hartree-Fock exchange energy gradients with respect to atomic positions and cell parameters at the Γ-point approximation is presented. While the...

Université de Fribourg

Application of the density functional theory derived orbital-free embedding potential to calculate the splitting energies of lanthanide cations in chloroelpasolite crystals

Zbiri, Mohamed ; Atanasov, Mihail ; Daul, Claude A. ; Garcia-Lastra, Juan Maria ; Wesolowski, Tomasz A.

In: Chemical Physics Letters, 2004, vol. 397(4-6), p. 441-446

Ligand field splitting energies of lanthanides Ln³⁺ (Ln = from Ce to Yb) in octahedral environment are calculated using the Hohenberg–Kohn theorems based orbital-free embedding formalism. The lanthanide cation is described at orbital level whereas its environment is represented by means of an additional term in the Kohn–Sham-like one-electron equations expressed as an explicit functional...

Université de Fribourg

Investigating the M*He exciplexes, M = {Li,Na,K,Rb,Cs,Fr}: Density functional approach

Zbiri, Mohamed ; Daul, Claude A.

In: Journal of Chemical Physics, 2004, vol. 121(23), p. 11625-11628

Potential curves for the ground and the first lowest excited states of the MHe (where M = {Li,Na,K,Rb,Cs,Fr}) exciplexes are calculated using the density functional theory (DFT) formalism. Relativistic calculations are carried out with and without spin-orbit (SO) coupling effect, using a zeroth order regular approximation (ZORA) approach. The depth De and position...

Université de Fribourg

Asymmetric μ2-1,1-azido bridged copper(II) complex: Synthesis, X-ray structure, magnetic study and DFT calculations

Zbiri, Mohamed ; Saha, Sandip ; Adhikary, Chandan ; Chaudhuri, Siddhartha ; Daul, Claude A. ; Koner, Subratanath

In: Inorganica Chimica Acta, 2006, vol. 359, p. 1193

A new rare variety asymmetric μ2-1,1-azido bridged copper(II) complex has been synthesized and characterized structurally and magnetically. The complex [Cu2L2(μ2-1,1-N3)2] · H2O · CH3OH (L = 1-(N-ortho-hydroxyacetophenimine)-2-aminoethane) (1), crystallizes in monoclinic space group, P21/n, with a = 9.469(4) Angstrom capital A, ring, b = 12.526(8) Angstrom capital A, ring, c = 12.899(10)...

Université de Fribourg

Density functional theory for the study of the multimode Jahn-Teller effect

Zlatar, Matija ; Gruden-Pavlović, Maja ; Schläpfer, Carl-Wilhelm ; Daul, Claude A.

In: Chimia, 2010, vol. 64, no. 3, p. 161-164

The Jahn-Teller (JT) theorem states that in a molecule with a degenerate electronic state, a structural distortion must occur that lowers the symmetry, removes the degeneracy and lowers the energy. The multideterminental-DFT method performed to calculate the JT parameters for JT active molecules is described. Within the harmonic approximation the JT distortion can be analyzed as a linear...

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

A new method to describe the multimode Jahn-Teller effect using density functional theory

Zlatar, Matija ; Schläpfer, Carl-Wilhelm ; Daul, Claude A.

In: Springer Series in Chemical Physics, 2010, vol. 97, p. 131-165

A new method for the analysis of the adiabatic potential energy surfaces of Jahn–Teller (JT) activemolecules is presented. It is based on the analogy between the JT distortion and reaction coordinates. Within the harmonic approximation the JT distortion can be analysed as the linear combination of all totally symmetric normal modes in the low symmetry minimum energy conformation. Contribution...