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arXiv 1609.03646cond-mat.stat-mech
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正则系统中的温度涨落:来自分子动力学模拟的启示

Temperature fluctuations in canonical systems: Insights from molecular dynamics simulations

J. Hickman, Y. Mishin

摘要:

准谐固体的分子动力学模拟进行阐明的意义,温度波动的正则系统和验证一个众所周知的,但经常有争议的方程预测的均方的这种波动。模拟实现两个虚拟和一个物理(自然)恒温器,并检查在时域和频域中的动能,势能和总能量关联函数。结果清楚地表明存在准平衡态,其中系统可以通过遵循上述波动方程的明确定义的温度来表征。这种状态的出现是由于声子散射的热弛豫和与恒温器的缓慢能量交换之间的时间尺度的广泛分离。当系统表现为虚孤立态和平衡态时,在这两个时间尺度之间存在准平衡态。

英文摘要:

Molecular dynamics simulations of a quasi-harmonic solid are conducted to elucidate the meaning of temperature fluctuations in canonical systems and validate a well-known but frequently contested equation predicting the mean square of such fluctuations. The simulations implement two virtual and one physical (natural) thermostat and examine the kinetic, potential and total energy correlation functions in the time and frequency domains. The results clearly demonstrate the existence of quasi-equilibrium states in which the system can be characterized by a well-defined temperature that follows the mentioned fluctuation equation. The emergence of such states is due to the wide separation of timescales between thermal relaxation by phonon scattering and slow energy exchanges with the thermostat. The quasi-equilibrium states exist between these two timescales when the system behaves as virtually isolated and equilibrium.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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