Refining Crystal Structures with Quadrupolar NMR and Dispersion-Corrected Density Functional Theory

Abstract

Nuclear electric field gradient (EFG) tensors obtained from solid-state NMR spectroscopy are highly responsive to variations in structural features. The orientations and principal components of EFG tensors show great variation between different molecular structures; hence, extraction of EFG tensor parameters, either experimentally or computationally, provides a powerful means for structure determination and refinement. Here, dispersion-corrected plane-wave density functional theory (DFT) is used to refine atomic coordinates in organic crystals determined initially through single-crystal X-ray diffraction (XRD) or neutron diffraction methods. To accomplish this, an empirical parametrization of a two-body dispersion force field is illustrated, in which comparisons of experimental and calculated 14N, 17O, and 35Cl EFG tensor parameters are used to assess the quality of energy-minimized structures. The parametrization is based on a training set of 17 organic solids. The analysis is applied subsequently to the...