Abstract：
BACKGROUND: We have performed a detailed MM and DFT investigation of neutral water clusters (H2O)n (n = 3-12). Our results show the trend of interaction energies in these clusters as a function of the size of the cluster. They show that the H-bond strength increases with cluster size and that the model of water is better described if two different partial charges are used on the hydrogen, depending on whether hydrogen is H-bonded or not. The average binding enthalpy change due to the formation of H-bonds between water molecules is found to be - 25.9 kJ mol-1 at B3LYP/aug-cc-pVDZ level of theory. We observe the formation of cyclic H-bonded networks through the analysis of frontier orbitals and IR vibrational frequencies spectra. For the water cluster with n = 11, we observe an unusual reduction of the bandgap indicative of a cyclic H-bonded network.
METHODS: Calculations were performed with the MMFF94 force field and the B3LYP method using various large basis sets. Molecular orbital diagrams and population analysis were done using standard tools in Gaussian.
METHODS: Calculations were performed with the MMFF94 force field and the B3LYP method using various large basis sets. Molecular orbital diagrams and population analysis were done using standard tools in Gaussian.
摘要：
背景：我们对中性水团簇（H2O）n（n=3-12）进行了详细的MM和DFT调查。我们的结果表明，这些团簇中相互作用能的趋势是团簇大小的函数。他们表明，H键强度随着簇大小而增加，并且如果在氢上使用两个不同的部分电荷，则可以更好地描述水的模型。取决于氢是否与H键合。在理论的B3LYP/aug-cc-pVDZ水平上，由于水分子之间形成H键而导致的平均结合焓变化为-25.9kJmol-1。通过对前沿轨道和红外振动频谱的分析，我们观察到环状H键网络的形成。对于n=11的水团簇，我们观察到带隙的异常降低，表明环状H键合网络。
方法：使用MMFF94力场和B3LYP方法使用各种大型基础集进行计算。使用高斯标准工具进行分子轨道图和群体分析。
方法：使用MMFF94力场和B3LYP方法使用各种大型基础集进行计算。使用高斯标准工具进行分子轨道图和群体分析。
