Snapshot of the d = 40 Å silica pore filled with water. Yellow spheres represent Si atoms, red spheres O atoms, and white spheres H atoms.
Density profiles of the centers-of-mass of water molecules vs. silica pore cross-sectional radius ρ.
H-bond radial density profiles for water in a 40 Å pore and in bulk liquid at 300 K. For water in the nanopore, the contributions from water-water, all water-silica H-bonds, and water-silica OH site H-bonds to the H-bond profile are also shown.
Angular probabilities for the orientations of water dipole and OH vectors relative to the outward surface normal. Results are shown for five 1 Å thick interfacial shells corresponding to the indicated ρ ranges.
Water mean squared displacements in the radial (top) and axial (bottom) directions in the silica nanopores. The MD data are compared to the fits to the “free diffusion in a cylinder” model.
Water MSDs in the axial (top) and radial (bottom) directions in four concentric interfacial layers (see text for the relevant ρ ranges) within 20 and 40 Å nanopores. Note that “surface–2” is a shell in the 40 Å pore and the innermost core region in the 20 Å pore.
Water local diffusion coefficients for motion in the radial (D ⊥) and axial (D ||) directions in different interfacial shells of the 40 Å nanopore.
Log-log plot of water MSDs in the axial (top) and radial (bottom) directions in four interfacial layers within the 20 Å nanopore and averaged over all the molecules in the pore.
Survival probabilities for water molecules in three comparable interfacial regions (outer, surface, and surface–1) of 40 Å and 20 Å silica nanopores.
Orientational time correlation C 2,OH(t) for water molecules in the three silica pores.
The orientational time correlation C 2, OH(t) for water molecules according to their initial location within the 30 Å pore. C 2, OH(t) for all the molecules in the nanopore and bulk water are also shown.
Water orientational time correlations C 2, OH(t) in the core (top) and outer (bottom) regions of nanopores of different diameters.
Hydrogen bond population time correlations in the 30 Å pore. The top panel displays the continuous and the bottom panel the intermittent H-bond time correlations.
The time correlations, , for relaxation of water-water H-bond continuous populations in 20 Å and 40 Å pores. In addition to total within the pore, the contributions from pairs of molecules in the interfacial and inner regions are shown.
Same as Figure 14, but for the intermittent water-water H-bond population time correlations, . The lower panel includes the results for bulk water.
Parameters used in silica nanopore construction.
System size parameters.
Fit parameters for the “free diffusion in a cylinder” model.
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