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arXiv 1312.4871physics.chem-phcond-mat.stat-mech
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过冷水ST2模型的两态热力学

Two-state thermodynamics of the ST2 model for supercooled water

Vincent Holten, Jeremy C. Palmer, Peter H. Poole, Pablo G. Debenedetti, Mikhail A. Anisimov

摘要:

ST 2模型的热力学性质的过冷液体水表现出类似于在真实的水观察到的异常。这些异常现象的一个可能的解释是存在一个亚稳态的,由临界点终止的液-液转变。这种现象,其可能存在于真实的水是目前许多实验工作的主题,已经明确地证明了这个特定的模型,最新的模拟。在这项工作中,我们再现了两个版本的ST 2模型的状态方程描述水作为一个非理想的“混合物”的两种不同类型的本地分子秩序的异常。我们表明,在ST 2水的液-液转变是能量驱动的。这与另一种流行的模型mW相反,在mW中,两种替代的局部分子顺序的混合的非理想性是熵驱动的,并且不足以强到诱导液-液转变。

英文摘要:

Thermodynamic properties of the ST2 model for supercooled liquid water exhibit anomalies similar to those observed in real water. A possible explanation of these anomalies is the existence of a metastable, liquid-liquid transition terminated by a critical point. This phenomenon, whose possible existence in real water is the subject of much current experimental work, has been unambiguously demonstrated for this particular model by most recent simulations. In this work, we reproduce the anomalies of two versions of the ST2 model with an equation of state describing water as a non-ideal "mixture" of two different types of local molecular order. We show that the liquid-liquid transition in the ST2 water is energy-driven. This is in contrast to another popular model, mW, in which non-ideality in mixing of two alternative local molecular orders is entropy-driven, and is not sufficiently strong to induce a liquid-liquid transition.

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