Nuclear quantum effects and hydrogen bond fluctuations in water

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Hydrogen bonds (HB) are fundamental to water's properties.
• Previous studies, often using classical simulations, have not fully captured quantum dynamics.

Purpose of the Study:

• To investigate the role of nuclear quantum effects on hydrogen bonds in liquid water.
• To explore transient proton dynamics and their impact on water's electronic structure.

Main Methods:

• Ab initio simulations incorporating nuclear quantum effects.
• Analysis of computed Wannier centers and (1)H chemical shifts.
• Comparison with simulations using classical nuclei.

Main Results:

• Protons in hydrogen-bonded water exhibit significant excursions toward acceptor oxygen atoms.
• Transient autoprotolysis events, absent in classical simulations, are observed.
• Quantum fluctuations show correlations across HBs, suggesting proton shuttling along water wires.
• Major electronic density rearrangements accompany these events.

Conclusions:

• Nuclear quantum effects are crucial for understanding proton dynamics in liquid water.
• Transient autoprotolysis and proton shuttling are key quantum phenomena in water.
• These findings may influence the understanding of how external factors affect water's hydrogen bond network.