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X-ray Absorption Spectral Signature of Quantum Nuclei in Liquid Water

preprint
submitted on 09.05.2018, 23:04 and posted on 10.05.2018, 14:48 by Zhaoru Sun, Lixin Zheng, Mohan Chen, Michael L. Klein, Francesco Paesani, Xifan Wu

Based on electron-hole excitation theory, we investigate the X-ray absorption spectral signature of nuclear quantum effect in liquid water, whose molecular structure is simulated by path-integral molecular dynamics using the MB-pol model. Compared to spectra generated from classically modeled water structure, quantum nuclei has important effect on spectra in terms of both the spectral energies and their line shapes. At the short-range ordering of H-bond network, the delocalized protons increase the fluctuations on the intramolecular covalency and broaden the pre-edge of the spectra. For intermediate-range and long-range orderings, the observed red and blue shifts of the main-edge and post-edge are attributed to the so-called competing quantum effects, under which both the weak and well-formed H-bonds are promoted. The theoretical spectra are in nearly quantitative agreement with the available experimental data.

Funding

National Science Foundation; U.S. Department of Energy

History

Email Address of Submitting Author

fpaesani@ucsd.edu

Email Address(es) for Other Author(s)

xifanwu@temple.edu

Institution

University of California San Diego

Country

United States

ORCID For Submitting Author

0000-0002-4451-1203

Declaration of Conflict of Interest

No conflict of interest.

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