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.
J Phys Condens Matter. 2013 Jun 26;25(25):255402. doi: 10.1088/0953-8984/25/25/255402. Epub 2013 May 29.
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.
扩展的 Czjzek 模型（ECM）被应用于通过分子动力学（MD）模拟获得的简单玻璃模型（偏磷酸钠，NaPO3）的 NMR 参数分布。通过在成熟的 PAW/GIPAW 框架内的密度泛函理论（DFT），精确计算了 NMR 张量、电场梯度（EFG）和化学位移各向异性（CSA）。将理论结果与实验高分辨率固态 NMR 数据进行比较，用于验证所考虑的结构模型。计算得到的耦合常数 C(Q)分布与 |V(zz)|成正比，讨论了用简单点电荷模型辅助的、描述四极相互作用的不对称参数 η(Q)，并根据结构考虑进行了讨论。最后，ECM 分析被证明对研究 CSA 张量参数的分布是相关的，并通过固态 NMR 为无序系统的结构特征提供了新的见解。
