Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements?
The quality of theoretical NMR shieldings calculated at the quantum-chemical level depends on various theoretical aspects, of which the basis set type and size are among the most important factors. Nevertheless, not much information is available on the basis set effect on theoretical shieldings of t...
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MDPI AG
2022-11-01
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author | Kacper Rzepiela Jakub Kaminský Aneta Buczek Małgorzata A. Broda Teobald Kupka |
author_facet | Kacper Rzepiela Jakub Kaminský Aneta Buczek Małgorzata A. Broda Teobald Kupka |
author_sort | Kacper Rzepiela |
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description | The quality of theoretical NMR shieldings calculated at the quantum-chemical level depends on various theoretical aspects, of which the basis set type and size are among the most important factors. Nevertheless, not much information is available on the basis set effect on theoretical shieldings of the NMR-active nuclei of the third row. Here, we report on the importance of proper basis set selection to obtain accurate and reliable NMR shielding parameters for nuclei from the third row of the periodic table. All calculations were performed on a set of eleven compounds containing the elements Na, Mg, Al, Si, P, S, or Cl. NMR shielding tensors were calculated using the SCF-HF, DFT-B3LYP, and CCSD(T) methods, combined with the Dunning valence aug-cc-pV<i>X</i>Z, core-valence aug-cc-pCV<i>X</i>Z, Jensen polarized-convergent aug-pcSseg-<i>n</i> and Karlsruhe x2c-Def2 basis set families. We also estimated the complete basis set limit (CBS) values of the NMR parameters. Widely scattered nuclear shieldings were observed for the Dunning polarized-valence basis set, which provides irregular convergence. We show that the use of Dunning core-valence or Jensen basis sets effectively reduces the scatter of theoretical NMR results and leads to their exponential-like convergence to CBS. We also assessed the effect of vibrational, temperature, and relativistic corrections on the predicted shieldings. For systems with single bonds, all corrections are relatively small, amounting to less than 4% of the CCSD(T)/CBS value. Vibrational and temperature corrections were less reliable for H<sub>3</sub>PO and HSiCH due to the high anharmonicity of the molecules. An abnormally high relativistic correction was observed for phosphorus in PN, reaching ~20% of the CCSD(T)/CBS value, while the correction was less than 7% for other tested molecules. |
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spelling | doaj.art-e97a72dfa4e24a14973ed33f0398994c2023-11-24T11:38:47ZengMDPI AGMolecules1420-30492022-11-012723823010.3390/molecules27238230Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements?Kacper Rzepiela0Jakub Kaminský1Aneta Buczek2Małgorzata A. Broda3Teobald Kupka4Faculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, PolandInstitute of Organic Chemistry and Biochemistry of the CAS, Flemingovo nám. 2, 166 10 Prague, Czech RepublicFaculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, PolandFaculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, PolandFaculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, PolandThe quality of theoretical NMR shieldings calculated at the quantum-chemical level depends on various theoretical aspects, of which the basis set type and size are among the most important factors. Nevertheless, not much information is available on the basis set effect on theoretical shieldings of the NMR-active nuclei of the third row. Here, we report on the importance of proper basis set selection to obtain accurate and reliable NMR shielding parameters for nuclei from the third row of the periodic table. All calculations were performed on a set of eleven compounds containing the elements Na, Mg, Al, Si, P, S, or Cl. NMR shielding tensors were calculated using the SCF-HF, DFT-B3LYP, and CCSD(T) methods, combined with the Dunning valence aug-cc-pV<i>X</i>Z, core-valence aug-cc-pCV<i>X</i>Z, Jensen polarized-convergent aug-pcSseg-<i>n</i> and Karlsruhe x2c-Def2 basis set families. We also estimated the complete basis set limit (CBS) values of the NMR parameters. Widely scattered nuclear shieldings were observed for the Dunning polarized-valence basis set, which provides irregular convergence. We show that the use of Dunning core-valence or Jensen basis sets effectively reduces the scatter of theoretical NMR results and leads to their exponential-like convergence to CBS. We also assessed the effect of vibrational, temperature, and relativistic corrections on the predicted shieldings. For systems with single bonds, all corrections are relatively small, amounting to less than 4% of the CCSD(T)/CBS value. Vibrational and temperature corrections were less reliable for H<sub>3</sub>PO and HSiCH due to the high anharmonicity of the molecules. An abnormally high relativistic correction was observed for phosphorus in PN, reaching ~20% of the CCSD(T)/CBS value, while the correction was less than 7% for other tested molecules.https://www.mdpi.com/1420-3049/27/23/8230NMR shieldingsbasis set dependencethird-row elements |
spellingShingle | Kacper Rzepiela Jakub Kaminský Aneta Buczek Małgorzata A. Broda Teobald Kupka Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements? Molecules NMR shieldings basis set dependence third-row elements |
title | Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements? |
title_full | Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements? |
title_fullStr | Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements? |
title_full_unstemmed | Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements? |
title_short | Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements? |
title_sort | electron correlation or basis set quality how to obtain converged and accurate nmr shieldings for the third row elements |
topic | NMR shieldings basis set dependence third-row elements |
url | https://www.mdpi.com/1420-3049/27/23/8230 |
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