TCM Group, Cavendish Laboratory, J J Thomson Avenue, Cambridge, CB3 0HE, UK.
Laboratory of Computational Science and Modeling, Institute of Materials, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.
Nat Commun. 2018 Jun 5;9(1):2173. doi: 10.1038/s41467-018-04618-6.
Ice is one of the most extensively studied condensed matter systems. Yet, both experimentally and theoretically several new phases have been discovered over the last years. Here we report a large-scale density-functional-theory study of the configuration space of water ice. We geometry optimise 74,963 ice structures, which are selected and constructed from over five million tetrahedral networks listed in the databases of Treacy, Deem, and the International Zeolite Association. All prior knowledge of ice is set aside and we introduce "generalised convex hulls" to identify configurations stabilised by appropriate thermodynamic constraints. We thereby rediscover all known phases (I-XVII, i, 0 and the quartz phase) except the metastable ice IV. Crucially, we also find promising candidates for ices XVIII through LI. Using the "sketch-map" dimensionality-reduction algorithm we construct an a priori, navigable map of configuration space, which reproduces similarity relations between structures and highlights the novel candidates. By relating the known phases to the tractably small, yet structurally diverse set of synthesisable candidate structures, we provide an excellent starting point for identifying formation pathways.
冰是被广泛研究的凝聚态物质系统之一。然而，在过去的几年中，无论是实验上还是理论上，都发现了几种新的相。在这里，我们报告了一个大规模的密度泛函理论研究水冰的构象空间。我们对 74963 种冰结构进行了几何优化，这些结构是从 Treacy、Deem 和国际沸石协会数据库中列出的超过五百万个四面体网络中选择和构建的。我们抛开所有关于冰的先验知识，并引入“广义凸包”来识别由适当的热力学约束稳定的构型。由此，我们重新发现了所有已知的相（I-XVII、i、0 和石英相），除了亚稳冰 IV。至关重要的是，我们还找到了通过十八到 LI 冰的有希望的候选者。使用“草图映射”降维算法，我们构建了一个先验的、可导航的构象空间地图，该地图再现了结构之间的相似关系，并突出了新的候选者。通过将已知的相联系到可合成的候选结构中结构差异较小但结构多样化的集合，我们为确定形成途径提供了一个极好的起点。
