Calculations of solid‐state ⁴³Ca NMR parameters: A comparison of periodic and cluster approaches and an evaluation of DFT functionals

Abstract

We present a computational study of magnetic-shielding and quadrupolar-coupling tensors of 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 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 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 Ca chemical-shift tensors. © 2017 Wiley Periodicals, Inc.

High‐resolution 13C and 43Ca solid‐state NMR and computational studies of the ethylene glycol solvate of atorvastatin calcium

“…Our previous computational study based on various model chemistries and more than 10 calcium‐containing crystals indicated that 43 Ca chemical‐shift and quadrupolar‐coupling calculations at the HF/cc‐pVTZ level probably offer the maximum benefits in terms of computational accuracy and computing time and resources . The 43 Ca chemical‐shift calculation at the HF/cc‐pVTZ level, based on a cluster model derived from the X‐ray single crystal structure of ATC‐EG with optimized hydrogen positions, agrees reasonably well with the experimental results (Table ).…”

“…Calculated 13 C magnetic‐shielding parameters were converted to the chemical‐shift scale using a referencing scheme summarized by Sefzik, Fidler, Iuliucci, and Facelli . Calculated 43 Ca shielding constants were converted to chemical‐shift values according to a computational survey of calcium‐containing materials . Euler angles were extracted from the Gaussian 09 output files using the program EFGShield …”

“…[18] Calculated 43 Ca shielding constants were converted to chemical-shift values according to a computational survey of calcium-containing materials. [19] Euler angles were extracted from the Gaussian 09 output files using the program EFGShield. [20] 3 | RESULTS AND DISCUSSION…”

“…Previous 13 C, 15 N, 19 F, and 43 Ca solid-state NMR (ssNMR) spectroscopic studies of atorvastatin [1,4] have provided NMR crystallographic information about ATC-I, which lacks a known crystal structure. A recent organogelation study of ATC [5] reveals that solvation of atorvastatin by a wide range of alkyl alcohols mostly leads to formation of organogels.…”

Which NICS method is most consistent with ring current analysis? Assessment in simple monocycles

“…This functional has been widely used for the calculation of magnetic properties in organic, inorganic and solid compounds, providing results comparable with experiments. 38,[54][55][56] Vibrational frequency calculations were performed at the same level to effectively obtain a true-minimum on the potential energy surface (PES), with the exception of the planar COT, which has one imaginary frequency (156.1i cm…”