Can hydrophobic interactions be correctly reproduced by the continuum models?

The ability of the continuum models to describe hydrophobic interactions is investigated. In this work we have studied the interactions between two methane molecules in aqueous solution by means of a continuum model. The resulting potential of mean force is in good agreement with those obtained using Monte Carlo and molecular dynamics techniques. The three energy contributions appearing in the continuum energy partition (electrostatic, dispersion-repulsion, and cavitation) have been analyzed. The cavitation free energy plays the most important role of the three, determining the existence of an energy barrier between the contact minimum and the separated methane monomers. This barrier, which also appears in previous molecular simulations, can only be reproduced using the solvent-excluding surface and not with the solvent-accessible surface.