Hydrophobic and Ionic Hydration Phenomenaa

Computer simulation offers an increasing opportunity to examine the details of solvation structure for well-defined solution models. One can characterize idealized models that exemplify specific aspects of solution behavior or those that realistically model systems experimentally difficult to access. As an example from the first category, results are presented for the aqueous solvation structure and solvent hydrogen bonding in the presence of a small apolar solute, and these are contrasted with the quite different behavior observed for a large apolar surface. As an example from the second category, structural results are presented for hydration of an excess electron in bulk water. These latter results, obtained via recent path integral simulation methods, manifest significant solvent structural disruption compared to the case of a simple ion, due to the irregular and fluctuating shape of the quantum solute.