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在冷式H和He中,N₂和O₂的核化率₂和He

Jiaou Song¹, Joseph D Berry¹, Eirini Goudeli¹

¹Department of Chemical Engineering, The University of Melbourne, Parkville, Melbourne, VIC 3052, Australia.

The journal of physical chemistry. B

|November 9, 2023

概括

经典分子动力学模拟显示了 (N2) 和氧 (O2) 在冷 (H2) 和 (He) 中的核化. 该研究量化了核化速率和关键集群大小,提供了对冷气体行为的见解.

科学领域:

物理化学物理化学
材料科学材料科学材料科学
计算物理计算物理

背景情况:

均质核化对于理解冷气体的相位过渡至关重要.
经典核化理论 (CNT) 在极端条件下预测核化动力学方面存在局限性.
含 (N2) 和氧 (O2) 在 (H2) 和 (He) 中的冷环境在各种工业和天体物理环境中都很重要.

研究的目的:

通过使用经典分子动力学 (MD) 模拟来研究冷H2和He中的N2和O2同质核化.
阐明核化动力学,包括核化速率,关键集群大小和集群能量.
将MD模拟结果与经典核化理论 (CNT) 预测进行比较.

主要方法:

经典分子动力学 (MD) 模拟被用来建模核化过程.
模拟涵盖了各种热化温度 (30-80 K) 和气体密度 (5.65 × 1024-2 × 1027 m−3) 的范围.
计算了关键核化参数,如核化速率 (Jsim),关键集群大小和集群能量.

主要成果:

模拟MD准确地捕获了核化过程中的能量释放,系统温度增加了77-138%.
计算的核化速率 (Jsim) 范围为2.14 × 1029到5.25 × 1036 m−3 s−1对于N2和O2.
MD结果显示在T < 70 K时与CNT一致,但在更高温度时显著分离 (3-7个数量级更快).
在低温温度 (<60K) 下,CNT预测的临界集群大小低于200-700%.
温度上升和蒸汽度下降导致了更大的临界集群大小.

结论:

经典分子动力学提供了一种可靠的方法,用于直接确定冷N2和O2系统中的核化速率和关键集群大小.
这项研究强调了在冷温度和更高温度下经典核化理论的局限性,特别是在关键集群大小预测方面.
这些发现提供了对冷却气体混合物中核化现象的更准确的理解,这对于完善理论模型和工业应用至关重要.

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