最小冰聚体结构单元模型及其对水性质影响的量化分析

Simulation of Minimum Ice Structural Unit and Quantitative Analysis of Its Effect on Water Properties

水的一些奇特性质主要源于水分子之间存在的氢键,但在分子尺度上的氢键结构和数据仍是目前研究和争论的焦点.统计分析了目前文献中普遍采用的水分子和氢键结构数据,并在此基础上应用AutoCAD图形软件模拟出(H2O)10结构的最小冰聚体结构单元(Minimum Ice Structural Unit,MISU)模型,以及由MISU聚合而成的冰晶体三维模型.根据MISU模型,可以计算得到冰在0℃融化为水、水由0℃加热至100℃、水在100℃汽化为水蒸气的三相转化过程中分别需要吸收5.86,4.40和24.94kJ·mol-1的能量以断裂16.7%,12.5%和70.8%的氢键.如若不考虑氢键的影响,那么计算得到水的融化热和汽化热分别为0.15和15.73kJ·mol-1,与VIA族氢化物H2S,H2Se,H2Te的融化热和汽化热基本呈线性关系.另外,由MISU模型计算得到冰在0℃融化为水时,密度由923.17kg·m-3增至999.89kg·m-3,亦与实际测量数据基本一致.

Based on the collection and selection of the parameters of water molecules and hydrogen bonds, configurations of a minimum ice structure unit （MISU） and ice crystal were simulated step by step thanks for the AutoCAD software. The simulation indicates that a minimum ice structure unit is made up of 10 H2O molecules in a four-hexagon cage structure. Based on the simulation, 1 mole of ice crystal contains 2 mole of hydrogen bonds, and 16.7% of hydrogen bonds （5.86 kJom·l^-1）, 12.5% of hydrogen bonds （4.40 kJom·l^-1） and 70.8% of hydrogen bonds （24.94 kJom·l^-1） should be broken during the processes of ice fusion at 0 ℃, watercalefaction from 0 to 100 ℃, and water vaporization at 100 ℃. The fusion and vaporization enthalpy values of water are 0.15 and 15.73 kJom·l^-1 respectively, which are consistent with the values of hydrides of Group VIA （H2O, H2S, H2Se, H2Te）. Density of ice 923.17 kg·m^-3 increased to that of water 999.89 kg·m^-3 during ice fusion at 0 ℃, which could also be calculated based on the MISU simulation.