Benchmarking density-functional-theory calculations of rotational g tensors and magnetizabilities using accurate coupled-cluster calculations

Abstract

'Benchmarking density-functional-theory calculations of rotational g tensors and magnetizabilities using accurate coupled-cluster calculations. ', Journal of chemical physics., 131 (14 ). p. 144104.Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. An accurate set of benchmark rotational g tensors and magnetizabilities are calculated using coupled-cluster singles-doubles ͑CCSD͒ theory and coupled-cluster single-doubles-perturbative-triples ͓CCSD͑T͔͒ theory, in a variety of basis sets consisting of ͑rotational͒ London atomic orbitals. The accuracy of the results obtained is established for the rotational g tensors by careful comparison with experimental data, taking into account zero-point vibrational corrections. After an analysis of the basis sets employed, extrapolation techniques are used to provide estimates of the basis-set-limit quantities, thereby establishing an accurate benchmark data set. The utility of the data set is demonstrated by examining a wide variety of density functionals for the calculation of these properties. None of the density-functional methods are competitive with the CCSD or CCSD͑T͒ methods. The need for a careful consideration of vibrational effects is clearly illustrated. Finally, the pure coupled-cluster results are compared with the results of density-functional calculations constrained to give the same electronic density. The importance of current dependence in exchange-correlation functionals is discussed in light of this comparison.

Calculated rotational and vibrational g factors of LiH X 1Σ+ and evaluation of parameters in radial functions from rotational and vibration‐rotational spectra

“…Our value of the rotational g factor at the separation Re is in perfect agreement with a recent benchmark CCSD(T) result [52] and our dipole moment radial function coincides with an earlier CISD [53] and very recent second order perturbation theory radial function [54]. Furthermore the satisfactory agreement between calculated and measured quantities, with deviations of less than 0.2%, demonstrates the quality of the radial functions for the rotational g factor and electric dipolar moment, and lends confidence to their use as constraints in fitting spectral data.…”

NMR shieldings from density functional perturbation theory: GIPAW versus all-electron calculations

“…As the shielding can be calculated as a second-order energy derivative, the same extrapolation has also been used for shieldings. [34][35][36] This extrapolation appears to work quite well for our DALTON results (Table S5 of the supplementary material). The maximal absolute deviation of the XY = Q5 extrapolation from the X = 5 results occurs for F 2 and is 0.4 ppm.…”

Molecular properties in the Tamm–Dancoff approximation: indirect nuclear spin–spin coupling constants

“…In Section 4.1, we initially consider 60 isotropic spin-spin couplings for 16 molecules at the CCSD(T)/ccpVTZ optimized geometries of Refs. [32,33] to assess the utility of the TDA; for further details of the systems considered, see the supplementary material. Here, we consider all possible couplings, irrespective of isotopic abundance, to maximize the number of data points in assessing the accuracy of the TDA.…”