Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan.
J Chem Phys. 2019 Jan 28;150(4):041102. doi: 10.1063/1.5083021.
Thermodynamic and mechanical stabilities of various ultralow-density ices are examined using computer simulations to construct the phase diagram of ice under negative pressure. Some ultralow-density ices, which were predicted to be thermodynamically metastable under negative pressures on the basis of the quasi-harmonic approximation, can exist only in a narrow pressure range at very low temperatures because they are mechanically fragile due to the large distortion in the hydrogen bonding network. By contrast, relatively dense ices such as ice Ih and ice XVI withstand large negative pressure. Consequently, various ices appear one after another in the phase diagram. The phase diagram of ice under negative pressure exhibits a different complexity from that of positive pressure because of the mechanical instability.
利用计算机模拟研究了各种超低密度冰的热力学和力学稳定性，以构建冰在负压下的相图。根据准谐近似，一些超低密度冰在负压下被预测为热力学亚稳相，但由于氢键网络的大变形，它们只能在非常低的温度下存在于很窄的压力范围内，因为它们的力学稳定性很差。相比之下，相对致密的冰，如冰 Ih 和冰 XVI，能够承受较大的负压。因此，各种冰在相图中相继出现。由于力学不稳定性，冰在负压下的相图表现出与正压下不同的复杂性。
