title: Calculation of chemical-shift tensors of heavy nuclei: a DFT/ZORA investigation of ¹⁹⁹Hg chemical-shift tensors in solids, and the effects of cluster size and electronic-state approximations.
abstract: Calculations of the nuclear magnetic resonance chemical-shielding tensors of a suite of mercury-containing materials using various cluster models for the structures provide a stringent test of the procedures for forming models and for calculation with various methods. The inclusion of higher co-ordination shells in the molecular clusters permits quantum chemical calculations of (199)Hg chemical-shielding tensor elements within 3% of the experimental values. We show that it is possible to reduce the size of computationally expensive molecular-cluster calculations with limited effect on calculated NMR parameters by carefully introducing the frozen core approximation. The importance of the relativistic Hamiltonian for accurate predictions of chemical-shielding values is demonstrated within the molecular cluster approach. The results demonstrate that careful design of a cluster to represent the solid-state structure, inclusion of relativistic components in the Hamiltonian at least at the spin-orbit level, and judicious use of approximations are essential to obtain good agreement with experimental results.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716-2522, USA. dybowski@udel.edu.
authors.forename: Fahri
authors.initials: F
authors.lastname: Alkan
authors.forename: C
authors.initials: C
authors.lastname: Dybowski