Guardia Elvira, Skarmoutsos Ioannis, Masia Marco
†Departament de Física i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Campus Nord B4-B5, Barcelona 08034, Spain.
‡INAC/SPrAM (UMR 5819 UJF, CNRS, CEA), CEA-Grenoble, 17 Rue des Martyrs, 38054 Grenoble, France.
J Phys Chem B. 2015 Jul 23;119(29):8926-38. doi: 10.1021/jp507196q. Epub 2014 Oct 31.
The local hydrogen-bonding structure and dynamics of liquid water have been investigated using the Car-Parrinello molecular dynamics simulation technique. The radial distribution functions and coordination numbers around water molecules have been found to be strongly dependent on the number of hydrogen bonds formed by each molecule, revealing also the existence of local structural heterogeneities in the structure of the liquid. The results obtained have also revealed the strong effect of the local hydrogen-bonding network on the local tetrahedral structure and entropy. The investigation of the dynamics of the local hydrogen-bonding network in liquid water has shown that this network is very labile, and the hydrogen bonds break and reform very rapidly. Nevertheless, it has been found that the hydrogen-bonding states associated with the formation of four hydrogen bonds by a water molecule exhibit the largest survival probability and corresponding lifetime. The reorientational motions of water molecules have also been found to be strongly dependent on their initial hydrogen-bonding state. Finally, the dependence of the librational and vibrational modes of water molecules on the local hydrogen-bonding network has been carefully examined, revealing a significant effect upon the libration and bond-stretching peak frequencies. The calculated low frequency peaks come in agreement with previously reported interpretations of the experimental low-frequency Raman spectrum of liquid water.
利用Car-Parrinello分子动力学模拟技术研究了液态水的局部氢键结构和动力学。发现水分子周围的径向分布函数和配位数强烈依赖于每个分子形成的氢键数量，这也揭示了液体结构中局部结构的不均匀性。所得结果还揭示了局部氢键网络对局部四面体结构和熵的强烈影响。对液态水中局部氢键网络动力学的研究表明，该网络非常不稳定，氢键断裂和重新形成非常迅速。然而，已发现与水分子形成四个氢键相关的氢键状态具有最大的生存概率和相应的寿命。还发现水分子的重排运动强烈依赖于它们最初的氢键状态。最后，仔细研究了水分子的摆动和振动模式对局部氢键网络的依赖性，揭示了对摆动和键拉伸峰频率的显著影响。计算得到的低频峰与先前报道的液态水实验低频拉曼光谱的解释一致。
