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Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Calculations of solid-state 43 Ca NMR parameters: A comparison of periodic and cluster approaches and an evaluation
Sean T Holmes1, Shi Bai1, Robbie J Iuliucci2
1Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, 19716.
Abstract:
We present a computational study of magnetic-shielding and quadrupolar-coupling tensors of 43 Ca sites in crystalline solids. A comparison between periodic and cluster-based approaches for modeling solid-state interactions demonstrates that cluster-based approaches are suitable for predicting 43 Ca NMR parameters. Several model chemistries, including Hartree-Fock theory and 17 DFT approximations (SVWN, CA-PZ, PBE, PBE0, PW91, B3PW91, rPBE, PBEsol, WC, PKZB, BMK, M06-L, M06, M06-2X, M06-HF, TPSS, and TPSSh), are evaluated for the prediction of 43 Ca NMR parameters. Convergence of NMR parameters with respect to basis sets of the form cc-pVXZ (X = D, T, Q) is also evaluated. All DFT methods lead to substantial, and frequently systematic, overestimations of experimental chemical shifts. Hartree-Fock calculations outperform all DFT methods for the prediction of 43 Ca chemical-shift tensors. © 2017 Wiley Periodicals, Inc.
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