Dresden 2011 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

HL: Fachverband Halbleiterphysik

HL 51: Joint Focussed Session: Theory and Computation of Electronic Structure: New Frontiers III

HL 51.3: Talk

Wednesday, March 16, 2011, 11:45–12:00, TRE Phy

First-principles quantum-mechanical methods for full prediction of NMR parameters in fluorides — •Aymeric Sadoc¹, Florent Boucher¹, Mamata Biswal², Monique Body², and Christophe Legein² — ¹Institut des matériaux Jean Rouxel (IMN) - Université de Nantes, CNRS, 2 rue de la houssinière, BP 32229, 44322 Nantes, France — ²Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels (IRIM2F) - Université du Maine, CNRS, Avenue Olivier Messiaen, 72085 Le Mans, France

¹⁹F magic angle spinning (MAS) NMR is a powerful structural tool for complex fluoride crystalline materials having multiple crystallographic sites since ¹⁹F (I=1/₂) isotropic chemical shift (δ_iso) is very sensitive to the environment of the fluorine atom. However, in many cases, several fluorine sites have the same multiplicity preventing an unambiguous experimental assignment. Simulation of the response to an external magnetic field is then necessary to complete the analysis. The relation of the measured δ_iso values with the calculated isotropic chemical shieldings (σ_iso) is needed to interpret of NMR spectra.

¹⁹F σ_iso values were calculated for alkali, alkaline earth and rare earth of column IIIB fluoride compounds using the GIPAW method implemented in the CASTEP software. Using DFT-PBE, we have established a linear relation between ¹⁹F calculated σ_iso and experimental δ_iso values which enables full prediction of ¹⁹F NMR spectra. In the case of complex NMR spectra, this calibration curve is successfully applied for the attribution from first-principles quantum-mechanical of ¹⁹F chemical shifts.