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Université de Fribourg

Electronic structure and photoluminescence properties of Eu(η9-C9H9)2

Ramanantoanina, Harry ; Merzoud, Lynda ; Muya, Jules Tshishimbi ; Chermette, Henry ; Daul, Claude

In: The Journal of Physical Chemistry A, 2020, vol. 124, no. 1, p. 152–164

The electronic structure of Eu2+ compounds results from a complex combination of strongly correlated electrons and relativistic effects as well as weak ligand–field interaction. There is tremendous interest in calculating the electronic structure as nowadays the Eu2+ ion is becoming more and more crucial, for instance, in lighting technologies. Recently, interest in semiempirical methods to...

Université de Fribourg

DFT investigation of methane metathesis with L2AnCH3 actinide complexes catalysts (L = Cl, Cp, Cp*; An = Ac, Th, Pa, U, Np, Pu)

Talbi-Ingrachen, Fazia ; Talbi, Fatiha ; Kias, Farida ; Elkechai, Aziz ; Boucekkine, Abdou ; Daul, Claude

In: Computational and Theoretical Chemistry, 2018, vol. 1138, p. 123–134

In order to understand the catalytic activity of the actinide complexes L2AnCH3 (An = Ac, Th, Pa, U, Np and Pu; L = Cl, Cp and Cp∗) towards the activation of the CH bond of methane, relativistic ZORA/DFT investigations have been carried out. The results obtained from Linear Transit (LT) and Intrinsic Reaction Coordinate (IRC) calculations show that the mechanism involved in these...

Université de Fribourg

A non-empirical calculation of 2p core-electron excitation in compounds with 3d transition metal ions using ligand-field and density functional theory (LFDFT)

Ramanantoanina, Harry ; Daul, Claude

In: Physical Chemistry Chemical Physics, 2017, vol. 19, no. 31, p. 20919–20929

Methodological advents for the calculation of the multiplet energy levels arising from multiple-open-shell 2p53dn+1 electron configurations, with n = 0, 1, 2,… and 9, are presented. We use the Ligand-Field Density Functional Theory (LFDFT) program, which has been recently implemented in the Amsterdam Density Functional (ADF) program package. The methodology consists of calculating the...

Université de Fribourg

Electronic fine structure calculation of metal complexes with three-open-shell s, d, and p configurations

Ramanantoanina, Harry ; Daul, Claude

In: Journal of Molecular Modeling, 2017, vol. 23, no. 8, p. 243

The ligand field density functional theory (LFDFT) algorithm is extended to treat the electronic structure and properties of systems with three-open-shell electron configurations, exemplified in this work by the calculation of the core and semi-core 1s, 2s, and 3s one-electron excitations in compounds containing transition metal ions. The work presents a model to non-empirically resolve the...

Université de Fribourg

Core electron excitations in U⁴⁺: modelling of the nd¹⁰5f² → nd⁹5f³ transitions with n = 3, 4 and 5 by ligand field tools and density functional theory

Ramanantoanina, Harry ; Kuri, Goutam ; Daul, Claude ; Bertsch, Johannes

In: Physical Chemistry Chemical Physics, 2016, vol. 18, no. 28, p. 19020–19031

Ligand field density functional theory (LFDFT) calculations have been used to model the uranium M4,5, N4,5 and O4,5-edge X-ray absorption near edge structure (XANES) in UO₂, characterized by the promotion of one electron from the core and the semi-core 3d, 4d and 5d orbitals of U⁴⁺ to the valence 5f. The model describes the procedure to resolve...

Université de Fribourg

Photoluminescence properties of Yb²⁺ ions doped in the perovskites CsCaX₃ and CsSrX₃ (X = Cl, Br, and I) – a comparative study

Suta, Markus ; Urland, Werner ; Daul, Claude ; Wickleder, Claudia

In: Physical Chemistry Chemical Physics, 2016, vol. 18, no. 19, p. 13196–13208

The Yb²⁺-doped perovskite derivatives CsMX₃ (M = Ca and Sr; X = Cl, Br, and I) are ideal systems for obtaining a detailed insight into the structure–luminescence relationship of divalent lanthanides. The investigation of the respective photoluminescence properties yielded two emission bands in the violet and blue spectral range for all compounds, which are assigned to the spin-allowed...

Université de Fribourg

Prospecting lighting applications with ligand field tools and density functional theory: a first-principles account of the 4f⁷–4f⁶5d¹ Luminescence of CsMgBr₃:Eu²⁺

Ramanantoanina, Harry ; Cimpoesu, Fanica ; Göttel, Christian ; Sahnoun, Mohammed ; Herden, Benjamin ; Suta, Markus ; Wickleder, Claudia ; Urland, Werner ; Daul, Claude

In: Inorganic Chemistry, 2015, vol. 54, no. 17, p. 8319–8326

The most efficient way to provide domestic lighting nowadays is by light-emitting diodes (LEDs) technology combined with phosphors shifting the blue and UV emission toward a desirable sunlight spectrum. A route in the quest for warm-white light goes toward the discovery and tuning of the lanthanide-based phosphors, a difficult task, in experimental and technical respects. A proper theoretical...

Université de Fribourg

On exchange coupling and bonding in the Gd2@C80 and Gd2@C79N endohedral dimetallo-fullerenes

Cimpoesu, Fanica ; Frecus, Bogdan ; Oprea, Corneliu I. ; Ramanantoanina, Harry ; Urland, Werner ; Daul, Claude

In: Molecular Physics, 2015, vol. 113, no. 13-14, p. 1712–1727

A series of computational experiments performed with various methods belonging to wave-function and density functional theories approaches the issue of bonding regime and exchange coupling in the title compounds. Gd₂@C₈₀ is computed with a very weak exchange coupling, the sign depending on the method, while Gd₂@C₇₉N has resulted with a strong coupling and ferromagnetic ground state,...