Matsumoto Masakazu, Yagasaki Takuma, Tanaka Hideki
Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan.
Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan.
J Chem Phys. 2021 Oct 28;155(16):164502. doi: 10.1063/5.0065215.
Pauling's successful estimation of the residual entropy of hydrogen-disordered ice was based on the homogeneity of the binding energy of individual water molecules in ice. However, it has not been explained why the binding energies are homogeneous although the pair interaction energy of hydrogen-bonded dimers distributes widely. Here, we provide a rationale for this phenomenon. The topological constraints imposed by the ice rules, in which water molecules form directed cyclic paths of hydrogen bonds, cancel out the variability of local interactions. We also show that the cancellation mechanism does not work due to some imperfect cyclic paths on the surface of ice. Such water molecules do not enjoy homogeneity in the bulk state and suffer from a wide spectrum in the binding energy.
鲍林对氢无序冰残余熵的成功估算基于冰中单个水分子结合能的均匀性。然而，尽管氢键二聚体的对相互作用能分布广泛，但结合能为何均匀却一直未得到解释。在此，我们为这一现象提供了一个合理的解释。冰规则所施加的拓扑约束，即水分子形成氢键的定向循环路径，抵消了局部相互作用的变异性。我们还表明，由于冰表面存在一些不完美的循环路径，这种抵消机制不起作用。这类水分子在体相中不具有均匀性，其结合能存在广泛的分布。
