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arXiv 1902.07710cond-mat.stat-mechcond-mat.soft
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物质超临界状态的热力学不均匀性和交叉

Thermodynamic heterogeneity and crossover in the supercritical state of matter

L. Wang, C. Yang, M. T. Dove, V. V. Brazhkin, K. Trachenko

摘要:

热力学相变的标志是系统热力学性质如能量和热容的质的变化。另一方面,没有相变被认为是在物质的超临界状态下进行的,因此,人们认为超临界热力学性质平滑地变化,没有任何质的变化。在这里,我们进行了广泛的分子动力学模拟在一个很宽的温度范围内,发现一个深超临界状态是热力学上的异质性,所见证的不同的温度依赖性的能量,热容及其衍生物在低温和高温。证据来自三种不同的分析方法,其中两种是独立于模型的。提出了热力学交叉点相对宽度的新定义,并计算出其相对宽度在13- 20%的较窄范围内。根据我们的研究结果,我们涉及的交叉超临界弗伦克尔线。

英文摘要:

A hallmark of a thermodynamic phase transition is the qualitative change of system thermodynamic properties such as energy and heat capacity. On the other hand, no phase transition is thought to operate in the supercritical state of matter and, for this reason, it was believed that supercritical thermodynamic properties vary smoothly and without any qualitative changes. Here, we perform extensive molecular dynamics simulations in a wide temperature range and find that a deeply supercritical state is thermodynamically heterogeneous, as witnessed by different temperature dependence of energy, heat capacity and its derivatives at low and high temperature. The evidence comes from three different methods of analysis, two of which are model-independent. We propose a new definition of the relative width of the thermodynamic crossover and calculate it to be in the fairly narrow relative range of 13-20\%. On the basis of our results, we relate the crossover to the supercritical Frenkel line.

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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