MOLECULAR-DYNAMICS CALCULATION OF THE EFFECT OF SOLVENT POLARIZABILITY ON THE HYDROPHOBIC INTERACTION

The potential of mean force (PMF) between two methane molecules in wat er is calculated using molecular dynamics with Ewald boundary conditio ns for two water models, the WK model (a nonpolarizable model) and the PSRWK model (a polarizable model), for the purpose of understanding w hat role many-body polarization plays in the hydrophobic interaction. These models of neat water have the same static dielectric constants a nd similar structural and thermodynamic properties. The methane-water interaction is taken to be exactly the same in both fluids. Neverthele ss, the simulated potential of mean force between two dissolved methan e molecules is very different for these two models. In the polarizable model, solvent-separated pairing is dominant over contact-pairing, wh ile in the nonpolarizable model the reverse is true.