Computer simulation of the hydrophobic hydration of concave surfaces

Hemispherical objects of radius from 6.5 to 12.2 Angstrom were constructed from tessellated icosahedra where the vertices were hydrophobic 'atoms'. These hemispheres were hydrated in a periodic box of water and molecular dynamics simulations in the NVE ensemble were performed on this solution at 320 K. Results show that water molecules in the concave region exhibit a layered structure and have their dipoles preferentially oriented approximately orthogonal to the radial direction of the hemisphere. They possess fewer hydrogen bonds and near neighbours. Changes in the translational dynamics of these water molecules are not detected, but there is an acceleration of the re-orientational dynamics. This work thus represents the first systematic study of the hydration of concave hydrophobic surfaces.