Ando Tadashi
Department of Applied Electronics, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan and Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
J Chem Phys. 2023 Sep 14;159(10). doi: 10.1063/5.0161476.
Water is a unique and abundant substance in biological and chemical systems. Considering its importance and ubiquity, numerous water models have been developed to reproduce various properties of bulk water in molecular simulations. Therefore, selecting an appropriate water model suitable for the properties of interest is crucial for computational studies of water systems. The four-point Optimal Point Charge (OPC) and three-point OPC (OPC3) water models were developed in 2014 and 2016, respectively. These models reproduce numerous properties of bulk water with high accuracy, such as density, dielectric constant, heat of vaporization, self-diffusion coefficient, and surface tension. In this study, we evaluated the shear viscosities of the OPC and OPC3 water models at various temperatures ranging from 273 to 373 K using the Green-Kubo formalism to assess their performance. The evaluated viscosities of both models were very close to each other at all the examined temperatures. At temperatures above 310 K, the calculated shear viscosities were in excellent agreement with the experimental results. However, at lower temperatures, the water models systematically underestimated the shear viscosity, with the calculated values at 273 and 298 K being 20% and 10% lower than the experimental values, respectively. Despite this limitation, the OPC and OPC3 water models outperformed other widely used water models.
水在生物和化学系统中是一种独特且丰富的物质。鉴于其重要性和普遍性，人们已开发出众多水模型，以便在分子模拟中重现大块水的各种性质。因此，选择一个适合所关注性质的水模型对于水系统的计算研究至关重要。四点最优电荷（OPC）水模型和三点OPC（OPC3）水模型分别于2014年和2016年被开发出来。这些模型能高精度地重现大块水的众多性质，如密度、介电常数、汽化热、自扩散系数和表面张力。在本研究中，我们使用格林 - 库博形式理论评估了OPC和OPC3水模型在273至373 K的各种温度下的剪切粘度，以评估它们的性能。在所有考察温度下，两个模型的评估粘度彼此非常接近。在高于310 K的温度下，计算得到的剪切粘度与实验结果高度吻合。然而，在较低温度下，水模型系统性地低估了剪切粘度，在273 K和298 K时计算值分别比实验值低20%和10%。尽管存在这一局限性，但OPC和OPC3水模型的表现优于其他广泛使用的水模型。
