Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA.
J Chem Phys. 2013 Jul 28;139(4):041103. doi: 10.1063/1.4817321.
At ambient conditions the intermolecular correlation in liquid water is generally believed to be short ranged as shown in the atomic pair distribution functions (PDFs) obtained from scattering experiments or from theoretical predictions. However, atom-atom PDFs provide only a partial description of the higher dimensional intermolecular correlation function that depends on both the positions and orientations of water molecules. Here we study the atomic PDFs of liquid water as well as the angular correlation function (ACF) using a classical density functional theory. We demonstrate that, different from the PDFs, the ACF exhibits long-range oscillatory decay extending up to tens of molecular diameters. The theoretical predictions are in good agreement with molecular simulations and corroborate recent experimental results from the second harmonic light scattering experiments.
在环境条件下，液体水中的分子间相关性通常被认为是短程的，这可以从散射实验或理论预测中获得的原子对分布函数 (PDF) 中看出。然而，原子对 PDF 仅提供了对依赖于水分子位置和取向的更高维分子间相关函数的部分描述。在这里，我们使用经典密度泛函理论研究了液体水的原子 PDF 以及角相关函数 (ACF)。我们证明，与 PDF 不同，ACF 表现出长程振荡衰减，延伸至数十个分子直径。理论预测与分子模拟吻合较好，并证实了最近来自二次谐波光散射实验的实验结果。
