Quadrupolar coupling: an introduction and crystallographic aspects

The quadrupolar coupling interaction is discussed in the context of the recent interest in determining crystallographic information by solid-state NMR. First, the nature of the quadrupolar interaction is reviewed and the first-principles calculation and experimental NMR measurement of quadrupolar couplings are discussed. Then, with these foundations in place, we describe how quadrupolar coupling parameters can be used to provide information about the arrangement of atoms in a crystalline solid. The topics discussed in this section include the effect of crystal symmetry, local structure, and solid-state dynamics upon quadrupolar parameters and how comparison of calculated and experimental parameters might be used to refine crystal structures derived from powder diffraction data