水合团簇离子的从头算分子动力学研究

项目名称： 水合团簇离子的从头算分子动力学研究

项目编号： No.21473151

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 刘志锋

作者单位： 香港中文大学深圳研究院

项目金额： 80万元

中文摘要： 水溶液的微观结构，一直是物理化学研究中的一个难题，因为通常溶液的实验只能得到统计平均。由一个溶质离子与数个水分子组成的水合团簇离子，为解决这一难题提供一条特殊的途径。这些团簇离子可以在气相生成与测量，通过改变水分子数目就可以调控微观溶化环境，尤如在气相搭起溶液的分子模型。最新发展出来的谱学实验技术，已经可以直接探测水合团簇离子的微观结构。理论化学计算是解释这些实验数据中必不可少的一环，但是传统量子化学计算中的结构优化与谐振分析却无法解析实验观察到的动力学效应。 我们计划以结合密度泛函与分子动力学的从头算分子动力学方法，模拟多原子酸根负离子的水合团簇随实时的演变，不但探索其结构的多重性，计算其自由能，并且直接模拟实验上观察到的动力学效应。这些酸根离子在自然界与生物体中都起着重要的作用，其水合团簇的实验研究已多有报道。我们的计算结果，将揭示这些离子的溶化动力学与溶化层形成的深层微观规律。

中文关键词： 量子化学计算；从头算分子动力学；水分子团簇；振动光谱；自由能计算

英文摘要： Understanding the microscopic details of solvation in aqueous solutions has been a challenge in physical chemistry, as only average quantities could be obtained in solution experiments. Hydrated ionic clusters, with a solute ion surrounded by a few water molecules, have provided a special way to meet this challenge. They are produced and probed in the gas phase, and their micro-solvation environment can be controlled by the number of water molecules, essentially providing a molecular model for solution. By the spectroscopic techniques developed in recent years, it is now possible to directly probe the micro-solvation details in such cluster ions. Theoretical calculations are an indispensable part of such studies, but the conventional quantum chemistry calculations based on optimized structures and harmonic analysis cannot account for the dynamic effects observed in experiments. We plan to apply the ab initio molecular dynamics method, which combines the density functional theory with molecular dynamic, to study the evolution of solvation structures in real time for poly-atomic anions solvated by water. The proposed simulations will not only probe the manifold of the potential surface for these clusters and calculate their free energy, but also analyze the experimentally observed an-harmonic and dynamic effects. These anions play important roles, both in the nature and in biological bodies, and their hydrated clusters have been the subject of many experimental studies. Our simulation results should provide insights into the underlying interactions governing the solvation dynamics and the formation of solvation shells for these anions.

英文关键词： Quantum Chemistry;Ab Initio Molecular Dynamics;Water Clusters;Vibrational Spectroscopy;Free Energy Calculations