Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom.
Proc Natl Acad Sci U S A. 2021 Mar 30;118(13). doi: 10.1073/pnas.2025245118.
The freezing of water into ice is one of the most important processes in the physical sciences. However, it is still not understood at the molecular level. In particular, the crystallization of cubic ice ([Formula: see text])-rather than the traditional hexagonal polytype ([Formula: see text])-has become an increasingly debated topic. Although evidence for [Formula: see text] is thought to date back almost 400 y, it is only in the last year that pure [Formula: see text] has been made in the laboratory, and these processes involved high-pressure ice phases. Since this demonstrates that pure [Formula: see text] can form, the question naturally arises if [Formula: see text] can be made from liquid water. With this in mind, we have performed a high-throughput computational screening study involving molecular dynamics simulations of nucleation on over 1,100 model substrates. From these simulations, we find that 1) many different substrates can promote the formation of pristine [Formula: see text]; 2) [Formula: see text] can be selectively nucleated for even the mildest supercooling; 3) the water contact layer's resemblance to a face of ice is the key factor determining the polytype selectivity and nucleation temperature, independent of which polytype is promoted; and 4) substrate lattice match to ice is not indicative of the polytype obtained. Through this study, we have deepened understanding of the interplay of heterogeneous nucleation and ice I polytypism and suggest routes to [Formula: see text] More broadly, the substrate design methodology presented here combined with the insight gained can be used to understand and control polymorphism and stacking disorder in materials in general.
水结冰是物理科学中最重要的过程之一。然而，在分子水平上仍然没有得到理解。特别是，立方冰（[Formula: see text]）的结晶——而不是传统的六方多型体（[Formula: see text]）——已经成为一个越来越有争议的话题。尽管立方冰（[Formula: see text]）的证据可以追溯到近 400 年前，但直到去年，实验室才首次制备出纯立方冰（[Formula: see text]），而且这些过程涉及高压冰相。由于这表明纯立方冰（[Formula: see text]）可以形成，自然而然地就会产生这样一个问题：是否可以从液态水中制备立方冰（[Formula: see text]）。考虑到这一点，我们进行了一项高通量计算筛选研究，涉及对超过 1100 个模型衬底上成核的分子动力学模拟。从这些模拟中，我们发现：1）许多不同的衬底可以促进原始立方冰（[Formula: see text]）的形成；2）即使是最轻微的过冷，也可以选择性地成核立方冰（[Formula: see text]）；3）水接触层与冰面相似是决定多型体选择性和成核温度的关键因素，与促进哪种多型体无关；4）衬底与冰的晶格匹配并不表示获得的多型体。通过这项研究，我们加深了对异质成核和冰 I 多型性相互作用的理解，并提出了制备立方冰（[Formula: see text]）的途径。更广泛地说，这里提出的衬底设计方法结合所获得的见解，可以用于理解和控制一般材料的多晶型性和堆积无序。
