液态水几何构型的分子动力学模拟

Molecular Dynamics Simulation for the Geometry of Water Molecule in Liquid

利用ＭＣＹＬ势对液态水进行分子动力学模拟，以探求近程和远程相互作用及液体的有序结构对水分子几何构型的影响，并确定对液态中水分子几何构型起作用的主要范围。模拟给出的液态水中原子对径向分布函数和水分子键长键角的变化与实验值能较好地符合。研究结果表明，液态水分子几何构型除与氢键的形成有关外，还与液体的近程有序结构有很大关系。键长的变化对这种近程有序结构虽不敏感，但键角的变化则对此非常灵敏。液态中第二水合层对键角的影响极为重要。

A molecular dynamics simulation for liquid water with the ab initio potential of water(MCYL)was applied to the investigation of the effects of the long and short-range interactions and of the liquid structure on the geometry of water molecule.The effective interaction ranges which influences the changes of the geometry of water molecule were also in vestigated.The simulated pair radial distribution functions of liquid water and the changes of the bond length and the bond angle of water molecule were compared well with those from experiments.The study shows that besides the effects of H-bond,the geometry of water molecule in liquid is greatly influenced by the order structure of the liquid.The changes in the bond angle of water molecule are very sensitive to the order structure of the liquid,while the changes in the bond length are not so.The second-nearest neighbors of a water molecule seem to play an important role in the changes of the bond angle.