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...

Université de Fribourg

Intrinsic distortion path in the analysis of the Jahn–Teller effect

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

In: Journal of Molecular Structure: THEOCHEM, 2010, vol. 954, p. 86-93

The multideterminental-DFT approach was performed in order to calculate the Jahn–Teller (JT) parameters for the JT active molecules. Within the harmonic approximation the JT distortion can be analysed as a linear combination of all totally symmetric normal modes in any of the low symmetry minimum energy conformation, which allows to calculate the Intrinsic Distortion Path (IDP), exactly from...

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

DFT Study of the Jahn-Teller Effect in Cu(II) Chelate Complexes

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

In: Journal of Molecular Structure: THEOCHEM, 2010, p. -

Density Functional Theory (DFT) in conjuction with the Intrinsic Distortion Path (IDP) is employed to study the Jahn-Teller (JT) effect in all four diastereoisomers of tris(ethylenediamine)copper(II) ([Cu(en)₃]²⁺) and tris(ethyleneglycol)copper(II) ([Cu(eg)₃]²⁺) complexes. As a consequence of the JT effect all the isomers tetragonally elongate to the C₂ configurations. Although there...

Université de Fribourg

Density functional theory study of the Jahn-Teller effect in cobaltocene

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

In: Pure and Applied Chemistry, 2009, vol. 81, no. 8, p. 1397-1411

A detailed discussion of the potential energy surface of bis(cyclopentadienyl)cobalt(II), cobaltocene, is given. Vibronic coupling coefficients are calculated using density functional theory (DFT). Results are in good agreement with experimental findings. On the basis of our calculation there is no second-order Jahn–Teller (JT) effect as predicted by group theory. The JT distortion can be...

Université de Fribourg

Poly(ethylene imine)-controlled Calcium Phosphate mineralization

Shkilnyy, Andriy ; Friedrich, Alwin ; Tiersch, Brigitte ; Schöne, Stefanie ; Fechner, Mabya ; Koetz, Joachim ; Schläpfer, Carl-Wilhelm ; Taubert, Andreas

In: Langmuir, 2008, vol. 24, no. 5, p. 2102–2109

The current paper shows that poly(ethylene imine) (PEI) is an efficient template for the fabrication of spherical calcium phosphate (CaP)/polymer hybrid particles at pH values above 8. The polymer forms spherical entities, which contain one or a few CaP particles with diameters of ca. 6 nm. The samples contain up to 20 wt % polymer, which appears to be wrapped around the small CaP particles. The...

Université de Fribourg

Polytopal rearrangement of [Ni(acac)₂(py)]: A new square pyramid ⇄ trigonal bipyramid twist mechanism

Daul, Claude ; Niketic, Svetozar ; Rauzy, Cédrick ; Schläpfer, Carl-Wilhelm

In: Chemistry - A European Journal, 2004, vol. 10(3), p. 721-727

The interconversion mechanisms between three idealized polytopal forms (a square pyramid and two trigonal bipyramids) of [M(bidentate)₂(unidentate)] were investigated by an original combination of molecular mechanics (MM) and density functional theory (DFT) approaches. MM was used to model the mechanistic rearrangement path, and DFT to study selected points along this path. The test case was a...

Université de Fribourg

Density functional study of nitroprusside: Mechanism of the photochemical formation and deactivation of the metastable states

Buchs, M. ; Daul, Claude A. ; Manoharan, P. T. ; Schläpfer, Carl-Wilhelm

In: International Journal of Quantum Chemistry, 2003, vol. 91 (3), p. 418-431

In this article, we present a theoretical investigation about the mechanism of the photochemical formation and deactivation of the metastable states observed in nitroprusside ions. The quantum chemical calculations are based on density functional theory. The peculiar photochemical and photophysical behavior of this molecule has attracted chemists' interest for a while. Due to this interest, many...