Kumar Pradeep, Buldyrev Sergey V, Starr Francis W, Giovambattista Nicolas, Stanley H Eugene
Center for Polymer Studies and Department of Physics Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Nov;72(5 Pt 1):051503. doi: 10.1103/PhysRevE.72.051503. Epub 2005 Nov 11.
We perform molecular dynamics simulations of 512 waterlike molecules that interact via the TIP5P potential and are confined between two smooth hydrophobic plates that are separated by 1.10 nm. We find that the anomalous thermodynamic properties of water are shifted to lower temperatures relative to the bulk by approximately 40 K. The dynamics and structure of the confined water resemble bulk water at higher temperatures, consistent with the shift of thermodynamic anomalies to lower temperature. Because of this T shift, our confined water simulations (down to T=220 K) do not reach sufficiently low temperature to observe a liquid-liquid phase transition found for bulk water at T approximately 215 K using the TIP5P potential, but we see inflections in isotherms at lower temperatures presumably due to the presence of a liquid-liquid critical point. We find that the different crystalline structures that can form for two different separations of the plates, 0.7 and 1.10 nm, have no counterparts in the bulk system, and we discuss the relevance to experiments on confined water.
我们对512个类水分子进行了分子动力学模拟，这些分子通过TIP5P势相互作用，并被限制在两个光滑的疏水板之间，两板间距为1.10纳米。我们发现，与本体水相比，受限水的反常热力学性质向更低温度偏移了约40K。受限水的动力学和结构在较高温度下类似于本体水，这与热力学反常向更低温度的偏移是一致的。由于这种温度偏移，我们对受限水的模拟（低至T = 220K）没有达到足够低的温度，从而无法观察到使用TIP5P势时本体水在T约为215K时出现的液 - 液相转变，但我们在更低温度下的等温线上看到了拐点，这可能是由于存在液 - 液临界点。我们发现，对于板间距为0.7纳米和1.10纳米这两种不同间距，可能形成的不同晶体结构在本体系统中没有对应物，并且我们讨论了其与受限水实验的相关性。
