Accurate sets of benchmark nuclear-magnetic-resonance shielding constants and spin–rotation constants are calculated using coupled-cluster singles–doubles (CCSD) theory and coupled-cluster singles–doubles–perturbative-triples [CCSD(T)] theory, in a variety of basis sets consisting of (rotational) London atomic orbitals. The accuracy of the calculated coupled-cluster constants is established by a careful comparison with experimental data, taking into account zero-point vibrational corrections. Coupled-cluster basis-set convergence is analyzed and extrapolation techniques are employed to estimate basis-set-limit quantities, thereby establishing an accurate benchmark data set. Together with the set provided for rotational g-tensors and magnetizabilities in our previous work [O. B. Lutnæs, A. M. Teale, T. Helgaker, D. J. Tozer, K. Ruud, and J. Gauss, J. Chem. Phys. 131, 144104 (2009)], it provides a substantial source of consistently calculated high-accuracy data on second-order magnetic response properties. The utility of this benchmark data set is demonstrated by examining a wide variety of Kohn–Sham exchange–correlation functionals for the calculation of these properties. None of the existing approximate functionals provide an accuracy competitive with that provided by CCSD or CCSD(T) theory. The need for a careful consideration of vibrational effects is clearly illustrated. Finally, the pure coupled-cluster results are compared with the results of Kohn–Sham calculations constrained to give the same electronic density. Routes to future improvements are discussed in light of this comparison.
Benchmarking density-functional theory calculations of NMR shielding constants and spin–rotation constants using accurate coupled-cluster calculations
Andrew M. Teale, Ola B. Lutnæs, Trygve Helgaker, David J. Tozer, Jürgen Gauss; Benchmarking density-functional theory calculations of NMR shielding constants and spin–rotation constants using accurate coupled-cluster calculations. J. Chem. Phys. 14 January 2013; 138 (2): 024111. https://doi.org/10.1063/1.4773016
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