In this work, we carried out a systematic and detailed study of water under severely confined conditions, based on atomistic molecular dynamics (MD) simulations. Specifically, MD simulations were performed for water confined in single-walled capped carbon nanotubes of chiral indices between (4,4) and (10,10). The structure and dynamics of confined water, and its dependence on the diameter and length of the capped carbon nanotubes (CCNTs) was examined, alongside with the influence of the latter on water immersion. Our results show that the axial water density decreases with increasing distance from the open face of the CCNTs, and that water forms well-defined shells along the radius of the CCNTs. The confined water molecules closer to the water–wall interfacial region tend to orient themselves pointing their OH bonds towards the wall. This trend becomes less evident in the inner regions of the CCNTs, so that the water molecules in the central region of the (10,10) CCNT are almost randomly oriented. On the other hand, the water molecules inside the (6,6) CCNT form a single-file chain along the CCNT's axis. Furthermore, the average number of hydrogen bonds per water molecule decreases with increasing length of the CCNT and decreasing diameter. Hydrogen bonding and water orientations in the CCNTs significantly affect the mobility of water, being the mobility of water faster in the (7,7) CCNT than in other CCNTs of the same length.

在这项工作中，我们基于原子分子动力学（MD）模拟对在严格受限条件下的水进行了系统且详细的研究。具体地说，对局限于手性指数在（4,4）和（10,10）之间的单壁封端碳纳米管中的水进行了MD模拟。研究了承压水的结构和动力学，及其对封端碳纳米管（CCNTs）直径和长度的依赖性，以及后者对水浸的影响。我们的结果表明，轴向水密度随与CCNT敞开面的距离增加而降低，并且水沿CCNT的半径形成轮廓分明的壳。靠近水-墙界面区域的受限水分子倾向于使自身定向，使其OH键指向壁。这种趋势在CCNT的内部区域变得不那么明显，因此（10,10）CCNT的中央区域中的水分子几乎是随机取向的。另一方面，（6,6）CCNT内部的水分子沿CCNT的轴形成单排链。此外，每个水分子的平均氢键数目随着CCNT长度的增加和直径的减小而降低。CCNT中的氢键和水的取向会显着影响水的迁移率，即（7,7）CCNT中的水迁移率快于相同长度的其他CCNT。6）CCNT沿CCNT的轴形成一个单文件链。此外，每个水分子的平均氢键数目随着CCNT长度的增加和直径的减小而降低。CCNT中的氢键和水的取向会显着影响水的迁移率，即（7,7）CCNT中的水迁移率快于相同长度的其他CCNT。6）CCNT沿CCNT的轴形成一个单文件链。此外，每个水分子的平均氢键数目随着CCNT长度的增加和直径的减小而降低。CCNT中的氢键和水的取向会显着影响水的迁移率，即（7,7）CCNT中的水迁移率快于相同长度的其他CCNT。