Molecular dynamics simulations of water confined in two hydrophilic cylindrical pores—PH and PL—that differ in their silanol surface concentration (7.6 and 3.0 nm⁻², respectively) have been performed at 300 K. A strong interaction of interfacial water molecules with the pore was systematically found and gives rise to a layering effect, a significant distortion of both the hydrogen bond network (HBN) and the tetrahedral structure of these water molecules, and a corresponding subdiffusive mean square displacement along the main axis of the pores. By contrast, water molecules in the inner part of both pores were found to behave similarly to bulk water. The HBN and the tetrahedral configuration of water were more gradually distorted in the PL pore given the larger heterogeneity and rugosity of the surface, and the number of water–pore hydrogen bonds did not scale linearly with the silanol surface concentration of the pores, in part because of the close proximity between silanols in the PH pore. With the PL pore, the dynamic slowing down of water was found consistent with the experiment, suggesting that it provides a better model for the cylindrical MCM-41 mesopores. The structural and dynamical properties of water vary little with the silica force field.

中文翻译：

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圆柱孔中的水：分子动力学研究。

限制在两个亲水性圆柱孔（PH 和 PL）中的水的分子动力学模拟，它们的硅烷醇表面浓度（7.6 和 3.0 nm ^-2, 分别) 已在 300 K 下进行。系统地发现界面水分子与孔隙的强相互作用并产生分层效应，这些水的氢键网络 (HBN) 和四面体结构均发生显着变形分子，以及相应的沿孔隙主轴的亚扩散均方位移。相比之下，发现两个孔内部的水分子的行为与本体水相似。考虑到表面的较大异质性和粗糙度，HBN 和水的四面体构型在 PL 孔中逐渐变形，并且水孔氢键的数量与孔的硅烷醇表面浓度不成线性比例，部分因为 PH 孔中的硅烷醇之间非常接近。随着PL孔，发现水的动态减慢与实验一致，表明它为圆柱形 MCM-41 中孔提供了更好的模型。水的结构和动力学性质随二氧化硅力场变化很小。