Nuclear Quantum Effects in Liquid Water Are Negligible for Structure but Significant for Dynamics
Abstract
Isotopic substitution, which can be realized both in experiment and computer simulations, is a direct approach to assess the role of nuclear quantum effects on the structure and dynamics of matter. Yet, the impact of nuclear quantum effects on the structure of liquid water as probed in experiment by comparing normal to heavy water has remained controversial. To settle this issue, we employ a highly accurate machine-learned high-dimensional neural network potential to perform converged coupled cluster-quality path integral simulations of liquid HO versus DO at ambient conditions. We find substantial H/D quantum effects on the rotational and translational dynamics of water, in close agreement with the experimental benchmarks. However, in stark contrast to the role for dynamics, H/D quantum effects turn out to be unexpectedly small, on the order of 1/1000 \r{A}, on both intramolecular and H-bonding structure of water. The most probable structure of water remains nearly unaffected by nuclear quantum effects, but effects on fluctuations away from average are appreciable, rendering HO substantially more "liquid" than DO.
Keywords
Cite
@article{arxiv.2410.17675,
title = {Nuclear Quantum Effects in Liquid Water Are Negligible for Structure but Significant for Dynamics},
author = {Nore Stolte and János Daru and Harald Forbert and Jörg Behler and Dominik Marx},
journal= {arXiv preprint arXiv:2410.17675},
year = {2024}
}