Based on quantum-mechanical path-integral molecular dynamics simulations the impact of nuclear quantum effects on the vibrational and hydrogen bond dynamics in liquid water is investigated. The instantaneous fluctuations in the frequencies of the O-H stretch modes are calculated using the wavelet method of time series analysis, while the time scales of the vibrational spectral diffusion are determined from frequency-time correlation functions, joint probability distributions, as well as the slope of three-pulse photon echo. We find that the inclusion of nuclear quantum effects leads not only to a redshift of the vibrational frequency distribution by around 130~cm−1, but also to an acceleration of the vibrational dynamics by as much as 30%. In addition, quantum fluctuations also entail a significantly faster decay of correlation in the initial diffusive regime, which is agreement with recent vibrational echo experiments.
@article{arxiv.1808.10270,
title = {Nuclear Quantum Effects on the Vibrational Dynamics of Liquid Water},
author = {Deepak Ojha and Andres Henao and Thomas D Kühne},
journal= {arXiv preprint arXiv:1808.10270},
year = {2018}
}