水分子团簇模拟及其在观测冷凝过程的应用

Water cluster simulation and its application in observing condensation

在气液相变过程中,水分子相互作用形成团簇,并产生分子间氢键,从而影响了羟基的振动频率。尺寸不同的团簇体系内氢键网络特性不同,红外吸收频率可反应OH所处的相邻氢键以及周围氢键的环境。本文采用密度泛函理论计算了不同尺寸水团簇的稳定结构和红外频率,分析了红外振动频率与团簇尺寸之间的演变关系。结果表明随着尺寸增大,内部水分子结构可能发生转变,(H2O)n团簇结构趋向于紧密的球形,并且伸缩振动频率向低频演化。研究结果可为通过红外光谱技术检测和确定团簇尺寸提供参考依据,并有可能用于水分子团簇在近壁区核化和生长7过程的量化检测。

In the initial nucleation process of vapor-liquid phase change, water molecules interact to form intermolecular hydrogen bonds that form clusters. The vibration frequency of hydroxyl group is affected and the hydrogen bond network is different in clusters with different sizes. In this paper, density functional theory was used to calculate the stable structure and infrared frequency of water clusters with different sizes, and the evolution relationship between infrared vibration frequency and cluster size was analyzed. Theoretical calculation results shows that with the increase of cluster size, the structure of(H2O)n tends to be compact and spherical, and the OH stretching vibration evolves to the low frequency. At the same time, the inner water substructure changes with the growth of clusters. The results can provide reference for detecting and determining the cluster size by infrared spectroscopy and may be used to observe and record the nucleation and growth process of water clusters in the near-wall region.