标题： 局部结构分析在$Ab$ $Initio$ 液态水中的应用 显示英文标题

标题： Local Structure Analysis in $Ab$ $Initio$ Liquid Water

摘要： 在密度泛函理论的框架下，包含精确交换和非局部范德华/色散（vdW）相互作用对于预测与实验定量一致的常压液态水的微观结构至关重要。 在本工作中，我们使用局域结构指数（LSI）序参数来分析这种高度准确的$ab$ $initio$ 液态水的局域结构。 在常压条件下，LSI 概率分布 P($I$) 是单峰的，大多数水分子表现出更无序的高密度类似局部环境。 在去除热激发后，固有势能面（IPES）中的 P($I$) 显示出高密度和低密度类似分子之间的 3:1 比例，后者形成小的相连簇，而前者是主要群体。 通过考虑具有相同 LSI 身份的水分子的空间相关性和氢键网络拓扑结构$among$，我们证明了实验观察到的低密度（LDA）和高密度（HDA）非晶冰相的特征存在于常压液态水的 IPES 中。 对 LSI 自相关函数的分析揭示了一个持续时间为$\sim$4 ps 的时间——这一发现与自然热涨落负责常压液态水中这些不同但短暂的局部水环境之间转换的事实是一致的。 显示英文摘要

摘要： Within the framework of density functional theory, the inclusion of exact exchange and non-local van der Waals/dispersion (vdW) interactions is crucial for predicting a microscopic structure of ambient liquid water that quantitatively agrees with experiment. In this work, we have used the local structure index (LSI) order parameter to analyze the local structure in such highly accurate $ab$ $initio$ liquid water. At ambient conditions, the LSI probability distribution, P($I$), was unimodal with most water molecules characterized by more disordered high-density-like local environments. With thermal excitations removed, the resultant bimodal P($I$) in the inherent potential energy surface (IPES) exhibited a 3:1 ratio between high- and low-density-like molecules, with the latter forming small connected clusters amid the predominant population. By considering the spatial correlations and hydrogen bond network topologies $among$ water molecules with the same LSI identities, we demonstrate that the signatures of the experimentally observed low- (LDA) and high-density (HDA) amorphous phases of ice are present in the IPES of ambient liquid water. Analysis of the LSI autocorrelation function uncovered a persistence time of $\sim$ 4 ps---a finding consistent with the fact that natural thermal fluctuations are responsible for transitions between these distinct yet transient local aqueous environments in ambient liquid water.