The curious case of the hydrated proton

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• The hydrated proton is crucial in chemistry, physics, and biology.
• Its anomalous diffusion is linked to Grotthuss shuttling, a complex molecular mechanism.
• Simulating these dynamics requires methods that handle changing chemical bonding topologies.

Purpose of the Study:

• To elucidate the molecular mechanisms of hydrated proton solvation and transport.
• To investigate the role of computer simulations in understanding these phenomena.
• To explore the behavior of hydrated protons in concentrated acid solutions.

Main Methods:

• Utilized ab initio molecular dynamics (AIMD) for high-accuracy simulations.
• Employed multistate empirical valence bond (MS-EVB) methodology for efficient, large-scale simulations.
• Parametrized MS-EVB using AIMD trajectories for multiscale modeling.

Main Results:

• Identified the distorted Eigen-type complex (H(9)O(4)(+)) as the most probable solvation structure.
• Described the "special-pair dance" as a preparatory phase for proton hopping.
• Revealed the amphiphilic nature of the hydrated proton, influencing its interface affinity and solubility behavior.

Conclusions:

• MS-EVB simulations provide efficient yet accurate insights into hydrated proton dynamics.
• The "special-pair dance" and amphiphilic character are key to understanding proton transport and solvation.
• Hydrated proton behavior in concentrated acids differs significantly from salt solutions.