Collective hydrogen-bond rearrangement dynamics in liquid water

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Hydrogen bonds in liquid water are crucial for its unique properties.
• Understanding collective hydrogen-bond rearrangements is key to elucidating water's dynamics.

Purpose of the Study:

• To investigate barrier-crossing processes in collective hydrogen-bond rearrangements in liquid water.
• To analyze the dynamics of water clusters without predefined hydrogen bond criteria.

Main Methods:

• Utilized Markov state modeling techniques on classical molecular dynamics simulation trajectories.
• Analyzed the complete 12-dimensional conformational subspace of three-water-molecule clusters.
• Accounted for full dynamics of relative angular and separation coordinates.

Main Results:

• Identified five well-separated slow dynamic processes (picosecond range) and a spectrum of faster modes.
• Markov eigenstate analysis linked processes to collective interchanges of hydrogen-bond donors and acceptors.
• Derived the complete hydrogen bond switching transition network, revealing direct and alternative pathways.

Conclusions:

• Collective hydrogen-bond rearrangements in water exhibit distinct slow dynamic processes.
• The most probable hydrogen bond switching pathway is direct, but alternative routes with intermediate states are significant.
• This work provides a detailed molecular-level understanding of hydrogen bond dynamics in liquid water.