title: Periodic ab initio calculation of nuclear quadrupole parameters as an assignment tool in solid-state NMR spectroscopy: applications to 23Na NMR spectra of crystalline materials.
abstract: Periodic ab initio HF calculations using the CRYSTAL code have been used to calculate (23)Na NMR quadrupole parameters for a wide range of crystalline sodium compounds including Na(3)OCl. An approach is developed that can be used routinely as an alternative to point-charge modelling schemes for the assignment of distinct lines in (23)Na NMR spectra to specific crystallographic sodium sites. The calculations are based on standard 3-21 G and 6-21 G molecular basis sets and in each case the same modified basis set for sodium is used for all compounds. The general approach is extendable to other quadrupolar nuclei. For the 3-21 G calculations a 1:1 linear correlation between experimental and calculated values of C(Q)((23)Na) is obtained. The 6-21 G calculations, including the addition of d-polarisation functions, give better accuracy in the calculation of eta((23)Na). The sensitivity of eta((23)Na) to hydrogen atom location is shown to be useful in testing the reported hydrogen-bonded structure of Na(2)HPO(4).
authors.affiliation: Department of Chemistry, Faculty of Science, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
authors.forename: Clive
authors.initials: C
authors.lastname: Johnson
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Moore
authors.forename: Michael
authors.initials: M
authors.lastname: Mortimer
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods; D003461:Crystallography / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D011208:Powders; D017670:Sodium Compounds / Q000032:analysis* / Q000737:chemistry*; D012975:Sodium Isotopes / Q000032:analysis / Q000737:chemistry
chemical_list: D011208:Powders; D017670:Sodium Compounds; D012975:Sodium Isotopes