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Université de Fribourg

The calculation of ESR parameters by density functional theory: the g- and A-tensors of Co(acacen)

Atanasov, Mihail ; Baerends, Evert Jan ; Baettig, Pio ; Bruyndonckx, Raf ; Daul, Claude A. ; Rauzy, Cédrick ; Zbiri, Mohamed

In: Chemical Physics Letters, 2004, vol. 399(4-6), p. 433-439

The new DFT based ligand field (LF) model is proposed to calculate the g- and A-tensors of [Co(acacen)] that is known to be a difficult case. The results obtained are compared with the ZORA approach implemented in ADF as well as with the experimental values. The calculations are in good agreement with the experimental data and demonstrate the ability of the method to reproduce the large...

Université de Fribourg

Calculation of spin-orbit coupling within the LFDFT: Applications to [NiX₄]²⁻ (X=F⁻, Cl⁻, Br⁻, I⁻)

Atanasov, Mihail ; Rauzy, Cédrick ; Baettig, Pio ; Daul, Claude A.

In: International Journal of Quantum Chemistry, 2005, vol. 102, p. 119-131

Spin-orbit coupling has been introduced into our newly developed ligand field density functional theory (LFDFT), using the zero-order regular approximation as implemented into the Amsterdam density functional (ADF) code. Application of the formalism to a series of NiX₄²⁻ (X=F⁻, Cl⁻, Br⁻, I⁻) compounds shows the increasing importance of intra-ligand spin-orbit coupling across the F,...

Université de Fribourg

DFT studies on the magnetic exchange across the cyanide bridge

Atanasov, Mihail ; Comba, Peter ; Daul, Claude A.

In: The Journal of Physical Chemistry A, 2006, vol. 110, no. 49, p. 13332 -13340

Exchange coupling across the cyanide bridge in a series of novel cyanometalate complexes with CuII-NC-MIII (M = Cr and low-spin Mn,Fe) fragments has been studied using the broken-symmetry DFT approach and an empirical model, which allows us to relate the exchange coupling constant with σ-, π-, and π*-type spin densities of the CN⁻ bridging ligand. Ferromagnetic...

Université de Fribourg

Ground States, Excited States and Metal-Ligand Bonding in Rare Earth Hexachloro Complexes: A DFT Based Ligand Field Study

Atanasov, Mihail ; Daul, Claude A. ; Güdel, Hans-Ulrich ; Wesolowski, Tomasz A. ; Zbiri, Mohamed

In: Inorganic Chemistry, 2005, vol. 44(8), p. 2954-2963

Metal (4f)-ligand (Cl 3p) bonding in LnCl63- (Ln = Ce to Yb) complexes has been studied on the basis of 4f->4f and Cl,3p->4f charge-transfer spectra and on the analysis of these spectra within the valence bond configuration interaction model to show that mixing of Cl 3p into the Ln 4f ligand field orbitals does not exceed 1%. Contrary to this, Kohn-Sham formalism...

Université de Fribourg

Chemical bonding in molecules and complexes containing d-elements based on DFT

Atanasov, Mihail ; Daul, Claude A. ; Fowe, E. Penka

In: Monatshefte für Chemie / Chemical Monthly, 2005, vol. 136(6), p. 925

Metal–ligand bonding in transition metal halide molecules and complexes with different central ions, oxidations states, and coordination numbers: CrIIIX₆³⁻, CrIVX₄, CrIIX₂ (X = F,Cl,Br,I), MIIICl₆³⁻(M = Mo,W), MIII(H₂O)₆³⁺(M = Cr,Co) and Re₂Cl₈²⁻ has been...

Consortium of Swiss Academic Libraries

Chemical Bonding in Molecules and Complexes Containing d-Elements Based on DFT

Atanasov, Mihail ; Daul, Claude A. ; Fowe, E. Penka

In: Monatshefte für Chemie / Chemical Monthly, 2005, vol. 136, no. 6, p. 925-963

Université de Fribourg

Modeling properties of molecules with open d-shells using density functional theory

Atanasov, Mihail ; Daul, Claude A.

In: Comptes Rendus Chimie, 2005, vol. 8(9-10), p. 1421-1433

An overview of the theory and applications of a recently proposed ligand-field density functional theory (LFDFT) is given. We describe a procedure based on DFT allowing to deduce the parameters of this non-empirical LF approach consisting of the following steps: (i) an average of configuration (AOC) DFT calculation, with equal occupancies of the d-orbitals is carried out (ii) with...

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(7-8), p. 504

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 of...

Université de Fribourg

A DFT based ligand field study of the EPR spectra of Co(II) and Cu(II) porphyrins

Atanasov, Mihail ; Daul, Claude A. ; Rohmer, Marie-Madeleine ; Venkatachalam, Tamilmani

In: Chemical Physics Letters, 2006, vol. 427, no. 4-6, p. 449-454

Using a DFT based Ligand Field treatment (LFDFT) of the electronic structure of Co(II) and Cu(II) porphyrins (CoP and CuP) we analyse the origin of their EPR spectra. From a comparison between theoretical result on Co model clusters (CoP and CoP–ZnP dimer) we conclude that the g-tensor values are very sensitive to the axial coordination which stabilizes a ²A₁ ground state in good...

Université de Fribourg

Combined ligand field and density functional theory analysis of the magnetic anisotropy in oligonuclear complexes based on FeIII−CN−MII exchange-coupled pairs

Atanasov, Mihail ; Comba, Peter ; Daul, Claude A.

In: Inorganic Chemistry, 2008, vol. 47, no. 7, p. 2449–2463

Magnetic anisotropy in cyanide-bridged single-molecule magnets (SMMs) with FeIII−CN−MII (M = Cu, Ni) exchange-coupled pairs was analyzed using a density functional theory (DFT)-based ligand field model. A pronounced magnetic anisotropy due to exchange was found for linear FeIII−CN−MII units with fourfold symmetry. This results from spin–orbit...