论文标题
NH $ _4^+$在水中的水合：分叉的氢键结构和快速旋转动力学
Hydration of NH$_4^+$ in Water: Bifurcated Hydrogen Bonding Structures and Fast Rotational Dynamics
论文作者
论文摘要
了解分子水平的水中离子的水合和扩散是一个广泛重要的话题。铵离子（NH $ _4^+$）是一个典范系统，由于其复杂的水合结构和行业相关性，它已经引起了数十年的关注。在这里，我们报告了使用Ab intible Molecular Dynamics模拟和量子蒙特卡罗计算的水合水合水合和NH $ _4^+$的旋转扩散。我们发现NH $ _4^+$的水合结构具有分叉的氢键，这导致旋转机制，涉及一对分叉的氢键同时切换。所提出的水合结构和旋转机制由现有的实验测量支持，它们还有助于合理化水中NH $ _4^+$的快速旋转。这项研究强调了氢键电子结构的细微变化如何影响水合结构，从而影响氢键系统中离子和分子的动力学。
Understanding the hydration and diffusion of ions in water at the molecular level is a topic of widespread importance. The ammonium ion (NH$_4^+$) is an exemplar system that has received attention for decades because of its complex hydration structure and relevance in industry. Here we report a study of the hydration and the rotational diffusion of NH$_4^+$ in water using ab initio molecular dynamics simulations and quantum Monte Carlo calculations. We find that the hydration structure of NH$_4^+$ features bifurcated hydrogen bonds, which leads to a rotational mechanism involving the simultaneous switching of a pair of bifurcated hydrogen bonds. The proposed hydration structure and rotational mechanism are supported by existing experimental measurements, and they also help to rationalize the measured fast rotation of NH$_4^+$ in water. This study highlights how subtle changes in the electronic structure of hydrogen bonds impacts the hydration structure, which consequently affects the dynamics of ions and molecules in hydrogen bonded systems.
