Published July 23, 2021 | Version v1
Dataset Open

The importance of nuclear quantum effects for NMR crystallography

  • 1. Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE UK
  • 2. Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
  • 3. Laboratory of Computational Science and Modeling, Institut des Matériaux, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Vaud, Switzerland

* Contact person

Description

The resolving power of solid-state nuclear magnetic resonance (NMR) crystallography depends heavily on the accuracy of the computational prediction of NMR chemical shieldings of candidate structures, which are usually taken to be local minima in the potential energy surface. To test the limits of this approximation, we perform a systematic study of the role of finite-temperature and quantum nuclear fluctuations on 1H, 13C, and 15N chemical shieldings in molecular crystals -- considering the paradigmatic examples of the different polymorphs of benzene, glycine, and succinic acid. We find the effect of quantum fluctuations to be comparable in size to the typical errors of predictions of chemical shieldings for static nuclei with respect to experimental measurements, and to improve the match between experiments and theoretical predictions, translating to more reliable assignment of the NMR spectra to the correct candidate structure. Thanks to the use of integrated machine-learning models trained on both first-principles configurational energies and chemical shieldings, the accurate sampling of thermal and quantum fluctuations of the structures can be achieved at an affordable cost, setting a new standard for the calculations that underlie solid-state structural determination by NMR. This archive contains the machine-learning potentials and shielding models, sample inputs, and scripts to reproduce the results discussed in the manuscript. It further contains the reference data and scripts to reconstruct the shielding models.

Files

File preview

files_description.md

All files

Files (1.7 GiB)

Name Size
md5:982c65d994257a891ab26aed96df9391
448 Bytes Preview Download
md5:5fc16e38c984272b79723996e3bcf38f
1.7 GiB Preview Download
md5:2f101c8781b793ef503fe16c3b818d95
6.9 KiB Download

References

Journal reference (Paper detailing the methodology and accordingly obtained results.)
E. A. Engel, V. Kapil, M. Ceriotti, Journal of Physical Chemistry Letters (submitted)