氢铵
化学
质子
氢氧化物
溶剂化
化学物理
分子动力学
密度泛函理论
离子
物理化学
无机化学
计算化学
有机化学
量子力学
物理
作者
Mohan Chen,Lixin Zheng,Biswajit Santra,Hsin-Yu Ko,Robert A. DiStasio,Michael L. Klein,Roberto Car,Xifan Wu
出处
期刊:Nature Chemistry
[Springer Nature]
日期:2018-03-09
卷期号:10 (4): 413-419
被引量:211
标识
DOI:10.1038/s41557-018-0010-2
摘要
Proton transfer via hydronium and hydroxide ions in water is ubiquitous. It underlies acid–base chemistry, certain enzyme reactions, and even infection by the flu. Despite two centuries of investigation, the mechanism underlying why hydroxide diffuses slower than hydronium in water is still not well understood. Herein, we employ state-of-the-art density-functional-theory-based molecular dynamics—with corrections for non-local van der Waals interactions, and self-interaction in the electronic ground state—to model water and hydrated water ions. At this level of theory, we show that structural diffusion of hydronium preserves the previously recognized concerted behaviour. However, by contrast, proton transfer via hydroxide is less temporally correlated, due to a stabilized hypercoordination solvation structure that discourages proton transfer. Specifically, the latter exhibits non-planar geometry, which agrees with neutron-scattering results. Asymmetry in the temporal correlation of proton transfer leads to hydroxide diffusing slower than hydronium. Even though the Grotthuss mechanism was proposed two centuries ago, it is still unclear why proton transfer via the hydroxide ion is slower than that via hydronium. Advanced ab initio molecular dynamics simulations now show that it is because proton transfer via hydroxide is less temporally correlated than transfer via hydronium.
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