Quantum diffusion of hydrogen and muonium atoms in liquid water and hexagonal ice.
Quantum diffusion of hydrogen and muonium atoms in liquid water and hexagonal ice.
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DOI：
10.1063/1.2925792
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发表时间：
2008-05
期刊：
影响因子：
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通讯作者：
T. Markland;S. Habershon;D. Manolopoulos
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文献类型：
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作者：
T. Markland;S. Habershon;D. Manolopoulos
我们用环状聚合物分子动力学方法研究了在较宽的温度范围(8-361K)内，在液态水和六角形冰中，Mu、H和H原子的扩散。与经典模拟预测的结果相比，量子效应显著地减少了钚在水中的扩散。这就简单地解释了为什么在观察到的这些物种在室温液体中的扩散系数中没有明显的同位素效应。我们的结果表明，液态水中的扩散机制类似于在冰中观察到的空穴间跳跃机制，并辅之以液体中空穴的扩散。在相同的模型中，我们还能够模拟观测到的氢和氢在六角形冰中的c轴扩散系数的交叉。最后，我们与实验数据得到了很好的一致，在8K，六方冰中的扩散过程完全是量子力学的。
We have used the ring polymer molecular dynamics method to study the diffusion of muonium, hydrogen, and deuterium atoms in liquid water and hexagonal ice over a wide temperature range (8-361 K). Quantum effects are found to dramatically reduce the diffusion of muonium in water relative to that predicted by classical simulation. This leads to a simple explanation for the lack of any significant isotope effect in the observed diffusion coefficients of these species in the room temperature liquid. Our results indicate that the mechanism of the diffusion in liquid water is similar to the intercavity hopping mechanism observed in ice, supplemented by the diffusion of the cavities in the liquid. Within the same model, we have also been able to simulate the observed crossover in the c-axis diffusion coefficients of hydrogen and deuterium in hexagonal ice. Finally, we have been able to obtain good agreement with experimental data on the diffusion of muonium in hexagonal ice at 8 K, where the process is entirely quantum mechanical.