Anomalous phase behavior of first-order fluid-liquid phase transition in phosphorus.
Anomalous phase behavior of first-order fluid-liquid phase transition in phosphorus.
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DOI：
10.1063/1.4999009
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发表时间：
2017-11
期刊：
影响因子：
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通讯作者：
G. Zhao;H. Wang;D. Hu;M. Ding;X. Zhao;J. L. Yan
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文献类型：
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作者：
G. Zhao;H. Wang;D. Hu;M. Ding;X. Zhao;J. L. Yan
尽管液-液相变的存在越来越令人信服，但它是否会在临界点终止以及序参量是多少仍然没有定论。为了探索这些问题，我们重新审视了磷（P）的液-液相变（FLPT），并通过进行广泛的第一性原理分子动力学模拟来研究其相行为。实验中观察到的FLPT很好地再现了，并在T = 3000 ~ 3500 K，P = 1.5-2.0 Kbar处发现了一个液-液临界点（FLCP），随着温度从FLCP沿着转变线降低，两共存相的密度差（Δρ）先从零开始增大，然后又逐渐减小;然而，熵差（ΔS）从零开始连续增加。这些特征表明，需要一个包含密度和熵贡献的序参数来描述P中的FLPT，并且至少在低温下，熵而不是密度支配FLPT。
Although the existence of liquid-liquid phase transition has become more and more convincing, whether it will terminate at a critical point and what is the order parameter are still open. To explore these questions, we revisit the fluid-liquid phase transition (FLPT) in phosphorus (P) and study its phase behavior by performing extensive first-principles molecular dynamics simulations. The FLPT observed in experiments is well reproduced, and a fluid-liquid critical point (FLCP) at T = 3000 ∼ 3500 K, P = 1.5-2.0 Kbar is found. With decreasing temperature from the FLCP along the transition line, the density difference (Δρ) between two coexisting phases first increases from zero and then anomalously decreases; however, the entropy difference (ΔS) continuously increases from zero. These features suggest that an order parameter containing contributions from both the density and the entropy is needed to describe the FLPT in P, and at least at low temperatures, the entropy, instead of the density, governs the FLPT.