Relativistic DFT Calculations of Copper Hyperfine Coupling Constants: Effect of Spin−Orbit Coupling

Abstract

Relativistic density functional theory (DFT) calculations of transition metal hyperfine interaction (A) tensors have been completed for a series of Cu2+ complexes including Cu(Quin)2, Cu(Acac)2, Cu(l-AlaO)2, and [Cu(Ox)2]2-. The A tensors were calculated with the zero order regular approximation (ZORA) for relativistic effects as implemented in the Amsterdam Density Functional (ADF) program. For the isotropic hyperfine coupling constant, the agreement between the calculated and experimental values was quite good, but the good agreement was determined to be a result of a cancellation of errors due to the neglect of spin−orbit coupling and an underestimation of core spin polarization. The anisotropic components of the hyperfine coupling constant calculated with the scalar-relativistic spin-restricted open-shell Kohn Sham (SO + SR ROKS) method provided the best agreement with experimental values.