Limmer David T, Chandler David
Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08540, USA.
Department of Chemistry, University of California, Berkeley, California 94609, USA.
J Chem Phys. 2014 Nov 14;141(18):18C505. doi: 10.1063/1.4895399.
Using statistical field theory supplemented with molecular dynamics simulations, we consider premelting on the surface of ice as a generic consequence of broken hydrogen bonds at the boundary between the condensed and gaseous phases. A procedure for coarse-graining molecular configurations onto a continuous scalar order parameter field is discussed, which provides a convenient representation of the interface between locally crystal-like and locally liquid-like regions. A number of interfacial properties are straightforwardly evaluated using this procedure such as the average premelting thickness and surface tension. The temperature and system size dependence of the premelting layer thickness calculated in this way confirms the characteristic logarithmic growth expected for the scalar field theory that the system is mapped onto through coarse-graining, though remains finite due to long-ranged interactions. Finally, from explicit simulations the existence of a premelting layer is shown to be insensitive to bulk lattice geometry, exposed crystal face, and curvature.
通过结合统计场论和分子动力学模拟，我们认为冰表面的预熔是凝聚相和气相间边界处氢键断裂的普遍结果。讨论了一种将分子构型粗粒化为连续标量序参量场的方法，该方法为局部类晶区和局部类液区之间的界面提供了一种方便的表示形式。利用该方法可以直接评估许多界面性质，如平均预熔厚度和表面张力。通过这种方式计算得到的预熔层厚度对温度和系统尺寸的依赖性证实了标量场论所预期的特征对数增长，即系统通过粗粒化被映射到该理论上，不过由于长程相互作用，该增长仍然是有限的。最后，通过显式模拟表明预熔层的存在对体晶格几何结构、暴露的晶面和曲率不敏感。
