title: Methodological aspects in the calculation of parity-violating effects in nuclear magnetic resonance parameters.
abstract: We examine the quantum chemical calculation of parity-violating (PV) electroweak contributions to the spectral parameters of nuclear magnetic resonance (NMR) from a methodological point of view. Nuclear magnetic shielding and indirect spin-spin coupling constants are considered and evaluated for three chiral molecules, H2O2, H2S2, and H2Se2. The effects of the choice of a one-particle basis set and the treatment of electron correlation, as well as the effects of special relativity, are studied. All of them are found to be relevant. The basis-set dependence is very pronounced, especially at the electron correlated ab initio levels of theory. Coupled-cluster and density-functional theory (DFT) results for PV contributions differ significantly from the Hartree-Fock data. DFT overestimates the PV effects, particularly with nonhybrid exchange-correlation functionals. Beginning from third-row elements, special relativity is of importance for the PV NMR properties, shown here by comparing perturbational one-component and various four-component calculations. In contrast to what is found for nuclear magnetic shielding, the choice of the model for nuclear charge distribution--point charge or extended (Gaussian)--has a significant impact on the PV contribution to the spin-spin coupling constants.
authors.affiliation: Laboratory of Physical Chemistry, Department of Chemistry, P.O. Box 55 (A.I. Virtasen aukio 1), University of Helsinki, FI-00014, Helsinki, Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Weijo
authors.forename: Radovan
authors.initials: R
authors.lastname: Bast
authors.forename: Pekka
authors.initials: P
authors.lastname: Manninen
authors.forename: Trond
authors.initials: T
authors.lastname: Saue
authors.forename: Juha
authors.initials: J
authors.lastname: Vaara