We investigated the structural, dynamical and spectroscopic properties of water molecules around a solvated methane by means of Car-Parrinello molecular dynamics simulations. Despite their mobility, in the first shell, water molecules are dynamically displaced in a clathrate-like cage around the hydrophobic solute. No significant differences in water geometrical parameters, in molecular dipole moments or in hydrogen bonding properties, are observed between in-shell and out-shell molecules, indicating that liquid water can accommodate a small hydrophobic solute without altering its structural properties. The calculated contribution of the first-shell water molecules to the infrared spectra does not show significant differences with respect the bulk signal once the effects of the missing polarization of second-shell molecules has been taken into account. Small fingerprints of the clathrate-like structure appear in the vibrational density of states in the libration and OH stretching regions.
Structural and Spectroscopic Properties of Water around Small Hydrophobic Solutes
GUIDONI, Leonardo
2012-01-01
Abstract
We investigated the structural, dynamical and spectroscopic properties of water molecules around a solvated methane by means of Car-Parrinello molecular dynamics simulations. Despite their mobility, in the first shell, water molecules are dynamically displaced in a clathrate-like cage around the hydrophobic solute. No significant differences in water geometrical parameters, in molecular dipole moments or in hydrogen bonding properties, are observed between in-shell and out-shell molecules, indicating that liquid water can accommodate a small hydrophobic solute without altering its structural properties. The calculated contribution of the first-shell water molecules to the infrared spectra does not show significant differences with respect the bulk signal once the effects of the missing polarization of second-shell molecules has been taken into account. Small fingerprints of the clathrate-like structure appear in the vibrational density of states in the libration and OH stretching regions.Pubblicazioni consigliate
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