Abstract The effects of angular momentum non-conservation in reverse non-equilibrium molecular dynamics (RNEMD) for thermal conductivity calculation are investigated. The velocity swapping operation in RNEMD results in an abnormal angular momentum flux when the center-of-mass velocity of heat source is considerable. The angular momentum is found to motivate a nonphysical wave motion at high heat flux, which was regarded as a novel heat conduction mechanism in earlier researches. This additional heat transport channel may lead to a nonphysical increase in the computed thermal conductivity. Therefore, we propose an improved RNEMD, in which the hottest/coldest atoms are selected in center-of-mass frames. The results show that the improved RNEMD can greatly reduce the nonphysical correlation at any heat flux, eliminate the wave motion mode, and give constant thermal conductivity. Our research reveals a nonphysical effect from angular momentum non-conservation in RNEMD, and provides an improved RNEMD for heat transport in solid materials.

中文翻译：

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RNEMD中角动量不守恒对计算热导率的影响及修正

摘要 研究了角动量不守恒在反向非平衡分子动力学 (RNEMD) 中对热导率计算的影响。当热源质心速度相当大时，RNEMD 中的速度交换操作会导致异常的角动量通量。角动量被发现在高热通量下激发非物理波动，这在早期的研究中被认为是一种新的热传导机制。这个额外的热传输通道可能导致计算出的热导率的非物理增加。因此，我们提出了一种改进的 RNEMD，其中在质心坐标系中选择最热/最冷的原子。结果表明，改进的 RNEMD 可以大大降低任何热通量下的非物理相关性，消除波动模式，并提供恒定的热导率。我们的研究揭示了 RNEMD 中角动量不守恒的非物理效应，并为固体材料中的热传输提供了改进的 RNEMD。