title: Extended Czjzek model applied to NMR parameter distributions in sodium metaphosphate glass.
abstract: The extended Czjzek model (ECM) is applied to the distribution of NMR parameters of a simple glass model (sodium metaphosphate, NaPO3) obtained by molecular dynamics (MD) simulations. Accurate NMR tensors, electric field gradient (EFG) and chemical shift anisotropy (CSA) are calculated from density functional theory (DFT) within the well-established PAW/GIPAW framework. The theoretical results are compared to experimental high-resolution solid-state NMR data and are used to validate the considered structural model. The distributions of the calculated coupling constant C(Q) is proportional to |V(zz)| and the asymmetry parameter η(Q) that characterize the quadrupolar interaction are discussed in terms of structural considerations with the help of a simple point charge model. Finally, the ECM analysis is shown to be relevant for studying the distribution of CSA tensor parameters and gives new insight into the structural characterization of disordered systems by solid-state NMR.
authors.affiliation: Unité de Catalyse et Chimie du Solide, UMR CNRS 8181, École Nationale Supérieure de Chimie de Lille, Université de Lille, BP Villeneuve d'Ascq, France. filipe.vasconcelos@cea.fr
authors.forename: Filipe
authors.initials: F
authors.lastname: Vasconcelos
authors.forename: Sylvain
authors.initials: S
authors.lastname: Cristol
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Paul
authors.forename: Laurent
authors.initials: L
authors.lastname: Delevoye
authors.forename: Francesco
authors.initials: F
authors.lastname: Mauri
authors.forename: Thibault
authors.initials: T
authors.lastname: Charpentier
authors.forename: Gérard
authors.initials: G
authors.lastname: Le Caër