The Importance of Nuclear Quantum Effects on the Thermodynamic and Structural Properties of Low-Density Amorphous Ice: A Comparison with Hexagonal Ice.
The Importance of Nuclear Quantum Effects on the Thermodynamic and Structural Properties of Low-Density Amorphous Ice: A Comparison with Hexagonal Ice.
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核量子效应对低密度非晶冰热力学和结构特性的重要性：与六角冰的比较。
DOI：
10.1021/acs.jpcb.3c01025
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Giovambattista,Nicolas
中科院分区：
文献类型：
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作者：
Eltareb,Ali;Lopez,GustavoE;Giovambattista,Nicolas
研究了低密度非晶冰（LDA）和六方冰（Ih）的核量子效应（NQE）对其热力学性质的影响。我们的研究结果基于路径积分分子动力学（PIMD）和使用q-TIP4P/F水模型的H2O和D2O的经典MD模拟。我们证明了NQE的加入对于再现LDA和iceIh的实验特性是必要的。MD模拟（没有NQE）预测LDA和iceIh的密度ρ(T)在冷却时单调增加，而PIMD模拟表明LDA和iceIh存在密度最大值。MD和PIMD模拟还预测了LDA和iceIh的热膨胀系数αP(T)和体积模量usb (T)在T依赖性上的定性不同。值得注意的是，LDA的ρ(T)、αP(T)和b (T)几乎与iceIh相同。观测到的NQE的起源是由于氢原子的离域，这在LDA和iceIh中是相同的。氢原子的离域（距离约为氢氧根共价键长度的20-25%）和各向异性（优先垂直于氢氧根共价键）显著降低，导致线性氢键HB（更大的HOO角和更长的OO分离）比经典MD模拟中观察到的要少。
We study the nuclear quantum effects (NQE) on the thermodynamic properties of low-density amorphous ice (LDA) and hexagonal ice (Ih) atP= 0.1 MPa andT≥ 25 K. Our results are based on path-integral molecular dynamics (PIMD) and classical MD simulations of H2O and D2O using the q-TIP4P/F water model. We show that the inclusion of NQE is necessary to reproduce the experimental properties of LDA and iceIh. While MD simulations (no NQE) predict that the density ρ(T) of LDA and iceIhincreases monotonically upon cooling, PIMD simulations indicate the presence of a density maximum in LDA and iceIh. MD and PIMD simulations also predict a qualitatively different T-dependence for the thermal expansion coefficient αP(T) and bulk modulusB(T) of both LDA and iceIh. Remarkably, the ρ(T), αP(T), andB(T) of LDA are practically identical to those of iceIh. The origin of the observed NQE is due to the delocalization of the H atoms, which is identical in LDA and iceIh. H atoms delocalize considerably (over a distance ≈ 20–25% of the OH covalent-bond length) and anisotropically (preferentially perpendicular to the OH covalent bond), leading to less linear hydrogen bonds HB (larger HOO angles and longer OO separations) than observed in classical MD simulations.