金纳米颗粒周围水的结构和动力学性质的分子动力学模拟

Molecular Dynamics Simulation of Structure and Dynamics Properties of Water Near an Au Nanoparticle

采用经典的分子动力学模拟方法系统地研究了在常温条件下金纳米颗粒周围水的结构与动力学性质.结果表明,水分子在纳米颗粒附近形成了明显的多层结构.同时随着径向距离的减小,水分子的空间取向也从无序排列趋向于有序排列.通过分析界面处不同水层中的均方位移及停留时间分布,发现紧贴颗粒表面的第一和第二水层中的水分子表现出很低的扩散系数,而第三和第四水层中的水分子则能够轻易地离开界面区域而进入主体相区域.此外,在界面处的每个水分子的氢键平均数要高于在主体相的平均值.

Classical molecular dynamics simulations were employed to investigate the structural and dynamical properties of water near an Au nanoparticle at room temperature. The simulation results showed that a well-defined multi-layered structure of water was formed close to the surface of the Au nanoparticle and the orientation of water molecules in the interfacial region changed gradually from the random arrangement to the ordered arrangement with the reduction in the radial distance. By analyzing the mean square displacement and occupation time distribution in different water layers, we found that water molecules in the first and second layers display very low diffusivity, whereas water molecules in the third and fourth layers could migrate from the interfacial region to the bulk region at short time. Additionally, the average number of hydrogen bonds per water molecule in the interfacial region was higher than that in the bulk phase.