We study in this paper the possible existence of Roskilde-simple liquids and their isomorphs in a rough-wall nanoconfinement. Isomorphs are curves in the thermodynamic phase diagram along which structure and dynamics are invariant in suitable nondimensionalized units. Two model liquids using molecular dynamics computer simulations are considered: the single-component Lennard-Jones (LJ) liquid and the Kob–Andersen binary LJ mixture, both of which in the bulk phases are known to have good isomorphs. Nanoconfinement is implemented by adopting a slit-pore geometry with fcc crystalline walls; this implies inhomogenous density profiles both parallel and perpendicular to the confining walls. Despite this fact and consistent with an earlier study [Ingebrigtsen et al., Phys. Rev. Lett., 2013, 111, 235901] we find that these two nanoconfined liquids have isomorphs to a good approximation. More specifically, we show good invariance along the isomorphs of inhomogenous density profiles, mean-square displacements, and higher-order structures probed using the topological cluster classification algorithm. Our study thus provides an alternative framework for understanding nanoconfined liquids.

中文翻译：

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纳米受限液体中的同构型

我们在本文中研究了在粗糙壁纳米限制中可能存在 Roskilde 简单液体及其同形体。同构是热力学相图中的曲线，沿着该曲线，结构和动力学在合适的无量纲化单位中是不变的。考虑了使用分子动力学计算机模拟的两种模型液体：单组分 Lennard-Jones (LJ) 液体和 Kob-Andersen 二元 LJ 混合物，这两种液体在本体相中都具有良好的同构型。纳米限制是通过采用具有 fcc 晶壁的狭缝孔几何结构来实现的；这意味着平行和垂直于围墙的密度分布不​​均匀。尽管有这个事实并且与早期的研究一致 [Ingebrigtsen et al. ，物理。牧师莱特。, 2013,111 , 235901] 我们发现这两种纳米限制液体具有很好的近似同构。更具体地说，我们在使用拓扑聚类分类算法探测的非均匀密度剖面、均方位移和高阶结构的同构中表现出良好的不变性。因此，我们的研究为理解纳米受限液体提供了一个替代框架。