发表机构
Ca’ Foscari University of Venice（威尼斯大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过粗粒化理论结合TIP4P/Ice水模拟，揭示偶极相互作用可触发或诱导过冷水的液-液相变，且该相变涉及第一配位壳的结构变化。
AI 中文摘要
偶极液体兼具平动与偶极两个耦合自由度，有趣的是，这两个自由度可处于不同的热力学状态，且其中一个自由度的状态可能会倾向于另一个自由度的特定状态，偶极液体中铁电序的出现便是这种相互稳定的实例。由于这种耦合通常编码在相互作用势中，通过投影去除一个自由度以推导另一个自由度的有效相互作用，可揭示该现象背后的微观机制。一种粗粒化理论显示，其中近邻粒子间的距离通过依赖密度的力学顺应性取决于它们的偶极相互作用，该理论表明铁电转变可触发液-液相变，还预测了顺电相中的一级液-液相变，而这种相变又可诱导铁电有序。各向异性的偶极依赖软核相互作用会产生一种类似Jagla的有效各向异性双长度尺度相互作用，已知该相互作用可支持液-液相变，但此处的双长度尺度模式取决于密度和偶极构型，对偶极序敏感。对过冷TIP4P/Ice水的数值模拟分析显示，对关联函数的第一配位壳特征对偶极相互作用敏感，支持了该粗粒化理论的基础。对比低密度和高密度液态水发现，低密度液态水的第一配位壳空间各向异性增强，有效排除体积增大，表明液-液相变涉及第一壳层内的结构变化，超出了间隙区域和四面体序的重组范围。这些发现表明偶极相互作用在过冷水的液-液相变中发挥作用。
英文摘要
Dipolar liquids combine two coupled degrees of freedom, translational and dipolar. Intriguingly, these two sectors can reside in distinct thermodynamic states, with the state of one sector possibly favoring a specific state of the other. The onset of ferroelectric order in dipolar liquids is an example of this mutual stabilization. Since this coupling is often encoded in interaction potentials, projecting out one sector to derive an effective interaction for the other can uncover the microscopic mechanism underlying this phenomenon. A coarse-grained theory in which the distance between nearest-neighbor particles depends on their dipolar interaction through a density-dependent mechanical compliance shows that a ferroelectric transition can trigger a liquid-liquid transition. It also predicts a first-order liquid-liquid transition in the paraelectric phase that can in turn induce ferroelectric ordering. The anisotropic dipolar-dependent soft-core interaction is shown to lead to an effective Jagla-like isotropic two-length-scale interaction, known to support liquid-liquid phase transitions. Here, however, the two-length-scale pattern depends on density and dipolar configuration, becoming sensitive to dipolar order. Analysis of supercooled TIP4P/Ice water numerical simulations shows that first-coordination-shell features of pair correlation functions are sensitive to dipolar interaction, supporting the coarse-grained theory foundations. Comparison of low- and high-density liquid water reveals enhanced spatial anisotropy of the first coordination shell in the low-density liquid, with increased effective excluded volume, showing that the liquid-liquid transition involves structural changes within the first shell, beyond reorganization of the interstitial region and tetrahedral order. These findings point to a role for dipolar interactions in supercooled water liquid-liquid phase transition.
