Weighted density functional theory of the solvophobic effect.

We are interested in the spatial density of a molecular fluid in the presence of a solute of arbitrary size and shape. The density functional is written as the sum of a F0[rho(r)] that effectively describes small deviations around the uniform density, plus an energy density part that is responsible for formation of liquid-vapor interface. Using the weighted density approach, we require the density functional to match with several observed properties of the fluid such as equation of state and surface tension. We also show that weighting functions for calculating the weighted density can be obtained from experimental data. Using these elements, we construct a spatial density functional theory of water and apply it to obtain densities and solvation energies of a hard-sphere solute with encouraging results.