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Thermodynamic Anomalies in Stretched Water
Langmuir ( IF 3.7 ) Pub Date : 2017-09-08 00:00:00 , DOI: 10.1021/acs.langmuir.7b02339 Y. Elia Altabet 1 , Rakesh S. Singh 1 , Frank H. Stillinger 2 , Pablo G. Debenedetti 1
Langmuir ( IF 3.7 ) Pub Date : 2017-09-08 00:00:00 , DOI: 10.1021/acs.langmuir.7b02339 Y. Elia Altabet 1 , Rakesh S. Singh 1 , Frank H. Stillinger 2 , Pablo G. Debenedetti 1
Affiliation
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Via molecular dynamics simulations of the TIP4P/2005 water model, we study liquid water’s anomalous behavior at large negative pressure produced through isochoric cooling. We find that isochores without a pressure minimum can display “reentrant” behavior whereby a system that cavitates upon cooling can then rehomogenize upon further cooling. This behavior is a consequence of the underlying density maximum along the spinodal, but its actual manifestation in simulations is strongly influenced by finite size effects. These observations suggest that water under strong hydrophilic confinement may display richer phase behavior than hitherto assumed. This also suggests that propensity toward cavitation does not always correlate with greater tension, contrary to the prevailing assumption for interpreting water stretching experiments. We also show that a maximum spinodal density in water results in a locus of maximum compressibility and a minimum speed of sound that are independent from any influence of a liquid–liquid critical point (LLCP). However, we demonstrate that structural signatures of a Widom line, which likely emanates from an LLCP at elevated pressure, extend to large negative pressure, but such signatures are only observed upon sampling water’s underlying potential energy landscape, rather than the thermalized metastable liquid.
中文翻译：
拉伸水中的热力学异常
通过TIP4P / 2005水模型的分子动力学模拟，我们研究了等压冷却在大负压下液态水的异常行为。我们发现，没有最小压力的等渗线可以表现出“折返”行为，从而在冷却时空化的系统可以在进一步冷却时重新均质。此行为是沿旋节线的潜在最大密度的结果，但是其在模拟中的实际表现受到有限尺寸效应的强烈影响。这些观察结果表明，在强亲水性约束下的水可能比迄今所假定的具有更丰富的相行为。这也表明，与解释水拉伸实验的普遍假设相反，对空化的倾向并不总是与更大的张力相关。我们还表明，水中最大旋节线密度导致最大可压缩性和最小声速的轨迹，而不受液-液临界点（LLCP）的任何影响。但是，我们证明了Widom线的结构特征（可能从LLCP高压发出）扩展到较大的负压，但是只有在对水的潜在势能图样而非热亚稳液体进行采样后才能观察到这种特征。
更新日期：2017-09-08
中文翻译：
拉伸水中的热力学异常
通过TIP4P / 2005水模型的分子动力学模拟，我们研究了等压冷却在大负压下液态水的异常行为。我们发现，没有最小压力的等渗线可以表现出“折返”行为，从而在冷却时空化的系统可以在进一步冷却时重新均质。此行为是沿旋节线的潜在最大密度的结果，但是其在模拟中的实际表现受到有限尺寸效应的强烈影响。这些观察结果表明，在强亲水性约束下的水可能比迄今所假定的具有更丰富的相行为。这也表明，与解释水拉伸实验的普遍假设相反，对空化的倾向并不总是与更大的张力相关。我们还表明，水中最大旋节线密度导致最大可压缩性和最小声速的轨迹，而不受液-液临界点（LLCP）的任何影响。但是，我们证明了Widom线的结构特征（可能从LLCP高压发出）扩展到较大的负压，但是只有在对水的潜在势能图样而非热亚稳液体进行采样后才能观察到这种特征。
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