Nuclear quantum effects on the thermodynamic, structural, and dynamical properties of water.
Nuclear quantum effects on the thermodynamic, structural, and dynamical properties of water.
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DOI：
10.1039/d0cp04325g
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发表时间：
2021-03-21
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影响因子：
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我们使用q-TIP4P/F模型对H2O和D2O进行了路径积分分子动力学（PIMD）模拟。模拟在P = 1 bar和广泛的温度范围内进行，包括水的平衡（T≥273 K）和过冷（210≤T < 273 K）液态。在平衡态和过冷态下，由PIMD模拟计算得到的H2O和D2O的密度与实验结果非常吻合。我们还评估了重要的热力学响应函数，即热膨胀系数αP(T)、等温压缩系数κT(T)、等压热容CP(T)和静态介电常数ε(T)。虽然这些性质与平衡状态下的实验结果[αP(T)和κT(T)]或半定量一致[CP(T)和ε(T)]，但随着进一步冷却，它们越来越被低估。由此可见，在（q-TIP4P/F）水的PIMD模拟中包含核量子效应不足以再现过冷水的密度、熵和电偶极矩特征的异常大波动。假设水在过冷状态下在pbbb1bar时可能出现液-液临界点（LLCP），这种LLCP在1bar时产生最大的CP(T)和κT(T)。与这一假设相一致，特别是与实验相一致，我们发现q-TIP4P/F轻水和重水的κT(T)在T≈230-235 K时达到最大值。在温度≥210 K时，CP(T)未见最大值。我们还利用环聚合物分子动力学（RPMD）技术计算了H2O和D2O的扩散系数D(T)，发现在所有研究温度下的计算机模拟与实验结果非常吻合。RPMD/PIMD模拟结果还与q-TIP4P/F水的经典MD模拟结果进行了比较，其中原子由单个相互作用位点表示。令人惊讶的是，我们发现在研究的大多数性质中存在微小差异，CP(T)， D(T)和结构性质是唯一的（预期的）例外。
We perform path-integral molecular dynamics (PIMD) simulations of H2O and D2O using the q-TIP4P/F model. Simulations are performed at P = 1 bar and over a wide range of temperatures that include the equilibrium (T ≥ 273 K) and supercooled (210 ≤ T < 273 K) liquid states of water. The densities of both H2O and D2O calculated from PIMD simulations are in excellent agreement with experiments in the equilibrium and supercooled regimes. We also evaluate important thermodynamic response functions, specifically, the thermal expansion coefficient αP(T), isothermal compressibility κT(T), isobaric heat capacity CP(T), and static dielectric constant ε(T). While these properties are in excellent [αP(T) and κT(T)] or semi-quantitative agreement [CP(T) and ε(T)] with experiments in the equilibrium regime, they are increasingly underestimated upon further cooling. It follows that the inclusion of nuclear quantum effects in PIMD simulations of (q-TIP4P/F) water is not sufficient to reproduce the anomalous large fluctuations in density, entropy, and electric dipole moment characteristic of supercooled water. It has been hypothesized that water may exhibit a liquid–liquid critical point (LLCP) in the supercooled regime at P > 1 bar and that such a LLCP generates a maximum in CP(T) and κT(T) at 1 bar. Consistent with this hypothesis and in particular, with experiments, we find a maximum in the κT(T) of q-TIP4P/F light and heavy water at T ≈ 230–235 K. No maximum in CP(T) could be detected down to T ≥ 210 K. We also calculate the diffusion coefficient D(T) of H2O and D2O using the ring-polymer molecular dynamics (RPMD) technique and find that computer simulations are in remarkable good agreement with experiments at all temperatures studied. The results from RPMD/PIMD simulations are also compared with the corresponding results obtained from classical MD simulations of q-TIP4P/F water where atoms are represented by single interacting sites. Surprisingly, we find minor differences in most of the properties studied, with CP(T), D(T), and structural properties being the only (expected) exceptions.
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DOI：
10.1073/pnas.1411620111
发表时间：
2014-12-09
影响因子：
11.1
作者：
Gainaru, Catalin;Agapov, Alexander L.;Sokolov, Alexei P.
通讯作者：
Sokolov, Alexei P.
影响因子：
4.4
作者：
Craig, IR;Manolopoulos, DE
通讯作者：
Manolopoulos, DE
DOI：
10.1073/pnas.1311718110
发表时间：
2013-10-29
影响因子：
11.1
作者：
Amann-Winkel, Katrin;Gainaru, Catalin;Loerting, Thomas
通讯作者：
Loerting, Thomas
影响因子：
4.4
作者：
Engstler, Justin;Giovambattista, Nicolas
通讯作者：
Giovambattista, Nicolas
影响因子：
4.4
作者：
Abascal, JLF;Vega, C
通讯作者：
Vega, C