Nuclear quantum delocalization enhances non-covalent intramolecular interactions: A machine learning and path integral molecular dynamics study

It is of common knowledge that nuclear quantum effects generates delocalized molecular dynamics. In this study, we present evidence that nuclear delocalization can enhance electronic and electrostatic interactions that promote localized dynamics. These results were obtained from the reconstructed potential-energy surfaces using the symmetrized gradient-domain machine learning (sGDML) framework[1] trained on coupled cluster with single, double, and perturbative triple excitations (CCSD(T)) data combined with path integral molecular dynamics simulations. The physical process responsible for this phenomenon is the effective reduction of the interatomic distances between non-covalently bonded atoms or functional groups. This potentiates intramolecular interactions such as the n→π* and electrostatic interactions[2]. These results diverge from the general assumption that nuclear quantum effects just tend to lower energetic barriers or to smoother the energy landscape, opening new avenues into possible explanations of complex processes in chemistry and biology.

[1] Chmiela et al. Sci. Adv. 3 (5), e1603015 (2017); Nat. Commun. 9 (1), 3887 (2108); Comput. Phys. Commun. 240, 38 (2019).
[2] Sauceda et al. J. Chem. Phys. 150 (11), 114102 (2019); arXiv:1909.08565 (2019).