纳米限域下甲烷-水体系的结构与动力学行为
Structural and dynamical behavior of methane-water systems under nanoconfinement
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中文总结 AI 辅助
通过分子动力学模拟研究1-5 nm孔宽下甲烷-水体系的结构与动力学，发现其对限域呈非单调依赖，存在特征限域尺度，强限域会抑制三维关联并阻碍成核。
中文摘要 AI 辅助
我们采用分子动力学模拟研究了纳米限域下甲烷-水体系的结构与动力学行为，研究的孔宽范围为1至5 nm。结构分析表明，该行为对限域具有强烈且非单调的依赖性：随着限域程度降低，四面体序部分恢复；而与笼型水合物前驱体相关的类立方序在中等孔尺寸时达到最大值。径向分布函数显示，强限域下三维关联被抑制，而侧向序依然存在，表明结构组织的有效维度降低。输运性质反映了相同的结构竞争：平行扩散随孔尺寸呈非单调变化，垂直运动因限域诱导的捕获与异质性表现为亚扩散；甲烷表现出更强的亚扩散行为，且与水基质保持动力学耦合。存在一个特征限域长度尺度，在此尺度下结构有序性、动力学异质性及溶剂-溶质解耦同时达到最大化。在强限域下，三维关联被抑制，导致维度降低、有序性受阻及成核被抑制。
英文摘要
We investigate the structural and dynamical behavior of methane water systems under nanoconfinement using molecular dynamics simulations across pore widths from 1 to 5 nm. Structural analysis reveals a strong and nonmonotonic dependence on confinement: while tetrahedral ordering partially recovers as confinement is reduced, cubic like order associated with clathrate precursors is maximized at intermediate pore sizes. Radial distribution functions show that three dimensional correlations are suppressed under strong confinement, whereas lateral ordering persists, indicating a reduction in the effective dimensionality of structural organization. Transport properties reflect the same structural competition. Parallel diffusion is nonmonotonic with pore size, while perpendicular motion is subdiffusive due to confinement induced trapping and heterogeneity. Methane exhibits stronger subdiffusion and remains dynamically coupled to the water matrix. A characteristic confinement length scale emerges at which structural ordering, dynamical heterogeneity, and solvent solute decoupling are simultaneously maximized. At strong confinement, three dimensional correlations are suppressed, leading to dimensional reduction, frustrated ordering, and inhibited nucleation.
