Nuclear spin-spin coupling constants from regular approximate relativistic density functional calculations. II. Spin-orbit coupling effects and anisotropies

This paper presents a full implementation of the zeroth order regular approximation (ZORA) hyperfine terms for nuclear spin-spin couplings into the Amsterdam Density Functional program, which allows the computations to be based on ZORA two-component spin-orbit coupled relativistic Kohn-Sham orbitals. An application to the calculation of one-bond couplings in some plumbanes shows that the spin-orbit contributions to the couplings are rather small for those systems, which is in agreement with results for PbH₄ obtained by others. Furthermore, spin-spin coupling constants and anisotropies are presented for the series XF (X=Cl, Br, I) and T1X (X=F, C1, Br, I), for which experimental and/or computational data are available. In addition, reported are coupling constants and anisotropies for the 'benchmark systems' ethane, ethene, and ethyne. Experimental trends are usually well reproduced, making DFT spin-spin coupling calculations favorable for systems where explicity correlated ab initio computations are too expensive and/or not feasible due to the lack of an explicit relativistic treatment.