Ravindra Pavan, Advincula Xavier R, Schran Christoph, Michaelides Angelos, Kapil Venkat
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
Department of Chemistry, Columbia University, 3000 Broadway, New York, NY, 10027, USA.
Nat Commun. 2024 Aug 24;15(1):7301. doi: 10.1038/s41467-024-51124-z.
The Bernal-Fowler ice rules stipulate that each water molecule in an ice crystal should form four hydrogen bonds. However, in extreme or constrained conditions, the arrangement of water molecules deviates from conventional ice rules, resulting in properties significantly different from bulk water. In this study, we employ machine learning-driven first-principles simulations to identify a new stabilization mechanism in nanoconfined ice phases. Instead of forming four hydrogen bonds, nanoconfined crystalline ice can form a quasi-one-dimensional hydrogen-bonded structure that exhibits only two hydrogen bonds per water molecule. These structures consist of strongly hydrogen-bonded linear chains of water molecules that zig-zag along one dimension, stabilized by van der Waals interactions that stack these chains along the other dimension. The unusual interplay of hydrogen bonding and van der Waals interactions in nanoconfined ice results in atypical proton behavior such as potential ferroelectric behavior, low dielectric response, and long-range proton dynamics.
伯纳尔-福勒冰规则规定，冰晶中的每个水分子应形成四个氢键。然而，在极端或受限条件下，水分子的排列偏离了传统的冰规则，导致其性质与 bulk 水有显著差异。在本研究中，我们采用机器学习驱动的第一性原理模拟来识别纳米受限冰相中的一种新的稳定机制。纳米受限的结晶冰不是形成四个氢键，而是可以形成一种准一维氢键结构，每个水分子仅表现出两个氢键。这些结构由水分子的强氢键线性链组成，这些链在一个维度上呈锯齿状，通过范德华相互作用在另一个维度上堆叠这些链而得以稳定。纳米受限冰中氢键和范德华相互作用的异常相互作用导致了非典型的质子行为，如潜在的铁电行为、低介电响应和长程质子动力学。
