Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 39: Focussed session: Theory and computation of electronic structure: new frontiers III (jointly with HL, DS)
O 39.3: Vortrag
Mittwoch, 16. März 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 (δiso) 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 δiso values with the calculated isotropic chemical shieldings (σiso) is needed to interpret of NMR spectra.
19F σiso 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 σiso and experimental δiso 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.