How van der Waals interactions determine the unique properties of water
How van der Waals interactions determine the unique properties of water
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DOI：
10.1073/pnas.1602375113
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发表时间：
2016-07-26
影响因子：
11.1
通讯作者：
Behler, Joerg
中科院分区：
文献类型：
--
作者：
Morawietz, Tobias;Singraber, Andreas;Behler, Joerg
尽管水分子之间的相互作用主要由强定向氢键（HBs）主导，但最近有人提出，相对较弱的各向同性范德华力（vdW）对于理解液态水和冰的性质至关重要。这一见解来自从头算计算机模拟，它提供了水在原子水平上的无偏描述，并提供了有关潜在分子力的信息。然而，这种模拟的高计算成本阻碍了系统地研究vdW力对水的热力学异常的影响。在这里，我们开发了有效的从头开始质量的神经网络电位，并使用它们来证明vdW相互作用对于水的密度最大值和其负融化体积的形成至关重要。这两种现象都可以用HB网络的柔韧性来解释，这是弱vdW力微妙平衡的结果，例如，导致冷却时第二溶剂化壳的明显膨胀，从而导致密度最大值。
Whereas the interactions between water molecules are dominated by strongly directional hydrogen bonds (HBs), it was recently proposed that relatively weak, isotropic van der Waals (vdW) forces are essential for understanding the properties of liquid water and ice. This insight was derived from ab initio computer simulations, which provide an unbiased description of water at the atomic level and yield information on the underlying molecular forces. However, the high computational cost of such simulations prevents the systematic investigation of the influence of vdW forces on the thermodynamic anomalies of water. Here, we develop efficient ab initio-quality neural network potentials and use them to demonstrate that vdW interactions are crucial for the formation of water's density maximum and its negative volume of melting. Both phenomena can be explained by the flexibility of the HB network, which is the result of a delicate balance of weak vdW forces, causing, e.g., a pronounced expansion of the second solvation shell upon cooling that induces the density maximum.