Chemical-shift tensors of heavy nuclei in network solids: a DFT/ZORA investigation of 207Pb chemical-shift tensors using the bond-valence method

Abstract

Accurate computation of ²⁰⁷Pb magnetic shielding principal components is within the reach of quantum chemistry methods by employing relativistic ZORA/DFT and cluster models adapted from the bond valence model.

Abstract

Cluster models are used in calculation of ²⁰⁷Pb NMR magnetic-shielding parameters of α-PbO, β-PbO, Pb ₃O ₄, Pb ₂SnO ₄, PbF ₂, PbCl ₂, PbBr ₂, PbClOH, PbBrOH, PbIOH, PbSiO ₃, and Pb ₃(PO ₄) ₂. We examine the effects of cluster size, method of termination of the cluster, charge on the cluster, introduction of exact exchange, and relativistic effects on calculation of magnetic-shielding tensors with density functional theory. Proper termination of the cluster for a network solid, including approximations such as compensation of charge by the bond-valence (BV) method, is essential to provide results that agree with experiment. The inclusion of relativistic effects at the spin–orbit level for such heavy nuclei is an essential factor in achieving agreement with experiment.