Calculation of chemical-shift tensors of heavy nuclei: a DFT/ZORA investigation of 199 Hg chemical-shift tensors in solids, and the effects of cluster size and electronic-state approximations
- Award ID(s):
- 0956006
- PAR ID:
- 10012665
- Date Published:
- Journal Name:
- Phys. Chem. Chem. Phys.
- Volume:
- 16
- Issue:
- 27
- ISSN:
- 1463-9076
- Page Range / eLocation ID:
- 14298 to 14308
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The ability to theoretically predict accurate NMR chemical shifts in solids is increasingly important due to the role such shifts play in selecting among proposed model structures. Herein, two theoretical methods are evaluated for their ability to assign15N shifts from guanosine dihydrate to one of the two independent molecules present in the lattice. The NMR data consist of15N shift tensors from 10 resonances. Analysis using periodic boundary or fragment methods consider a benchmark dataset to estimate errors and predict uncertainties of 5.6 and 6.2 ppm, respectively. Despite this high accuracy, only one of the five sites were confidently assigned to a specific molecule of the asymmetric unit. This limitation is not due to negligible differences in experimental data, as most sites exhibit differences of >6.0 ppm between pairs of resonances representing a given position. Instead, the theoretical methods are insufficiently accurate to make assignments at most positions.more » « less
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