Departamento de Física, UFSCar, Rodovia Washington Luiz, km 235, CP 676, São Carlos, 13565-905 São Paulo, Brazil.
Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas, Universidade Federal do ABC, Santo André, 09210-580 São Paulo, Brazil.
J Chem Phys. 2019 Jan 28;150(4):044503. doi: 10.1063/1.5082743.
Using molecular dynamics simulations, we compute the elastic constants of ice I for a set of 8 frequently used semi-empirical potentials for water, namely, the rigid-molecule SPC/E, TIP4P, TIP4P2005, TIP4P/Ice, and TIP5P models, the flexible-molecule qTIP4P/Fw and SPC/Fw models, and the coarse-grained atomic mW potential. In quantitative terms, the mW description gives values for the individual stiffness constants that are closest to the experiment, whereas the explicit-proton models display substantial discrepancies. On the other hand, in contrast to all explicit-proton potentials, the mW model is unable to reproduce central qualitative trends such as the anisotropy in Young's modulus and the shear modulus. This suggests that the elastic behavior of ice I is closely related to its molecular nature, which has been coarse-grained out in the mW model. These observations are consistent with other recent manifestations concerning the limitations of the mW model in the description of mechanical properties of ice I.
利用分子动力学模拟，我们计算了 8 种常用的水半经验势能的冰 I 的弹性常数，分别是刚性分子 SPC/E、TIP4P、TIP4P2005、TIP4P/Ice 和 TIP5P 模型、柔性分子 qTIP4P/Fw 和 SPC/Fw 模型以及粗粒化原子 mW 势。从定量的角度来看，mW 描述给出的单个弹性常数值与实验最接近，而显质子模型则存在显著差异。另一方面，与所有显质子势不同，mW 模型无法再现杨氏模量和剪切模量等弹性常数的各向异性等重要定性趋势。这表明冰 I 的弹性行为与其分子性质密切相关，而 mW 模型已经将其粗粒化。这些观察结果与其他最近关于 mW 模型在描述冰 I 的力学性质方面的局限性的表现一致。
