Dynamical Accuracy of Water Models on Supercooling.,The Journal of Physical Chemistry Letters

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Dynamical Accuracy of Water Models on Supercooling.
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2020-08-11 , DOI: 10.1021/acs.jpclett.0c02158
Thomas O Farmer ₁ , Anders J Markvardsen ₁ , Thomas H Rod ₂ , Heloisa N Bordallo _{3,

4} , Jan Swenson ₅

Affiliation

Molecular dynamics (MD) simulations are commonly used to explore the structural and dynamical properties of supercooled bulk water in the so-called “no man’s land” (NML) (150–227 K), where crystallization occurs almost instantaneously. This approach has provided significant insight into experimentally inaccessible phenomena. In this paper, we compare the dynamics of simulations using one-, three-, and four-body water models to experimentally measured quasielastic neutron scattering spectra. We show that the agreement between simulated and experimental data becomes substantially worse with a decrease in temperature toward the deeply supercooled regime. It was found that it is mainly the nature of the local dynamics that is poorly reproduced, as opposed to the macroscopic properties such as the diffusion coefficient. This strongly implies that the molecular mechanism describing the water dynamics is poorly captured in the MD models, and simulated structural and dynamical properties of supercooled water in NML must be interpreted with care.

中文翻译：

过冷水模型的动态精度。

分子动力学（MD）模拟通常用于探索所谓“无人区”（NML）（150–227 K）中过冷的散装水的结构和动力学特性，在该处，结晶几乎是瞬间发生的。这种方法为实验上无法达到的现象提供了重要的见识。在本文中，我们将使用一体，三体和四体水模型的模拟动力学与实验测量的准弹性中子散射光谱进行了比较。我们表明，随着温度的升高，朝着深过冷状态的降低，模拟和实验数据之间的一致性变得越来越差。已经发现，主要是局部动力学的性质难以再现，这与诸如扩散系数的宏观特性相反。

更新日期：2020-09-18

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