Coarse-grained models for the solvents dimethyl sulfoxide, chloroform, and methanol.

The time- and length-scale accessible to molecular dynamics simulations of biomolecular systems using atomic-level (AL) models is most limited by the calculation of the solvent-solvent interactions, which comprise the majority of the interactions and yet are seldom of specific interest. Coarse-graining (CG), in which multiple solvent molecules are subsumed into a single bead, provides a means of overcoming this limitation without resorting to implicit solvation models, which basically misrepresent the hydrophobic effect. Most existing CG models, however, do not explicitly include electrostatic interactions, and thus fail to reproduce important properties of the solvent such as dielectric screening. Moreover, CG models for one type of solvent molecule are seldom compatible with those for other solvents. Here, we develop polarizable CG models for the solvents dimethyl sulfoxide, chloroform, and methanol that are compatible with an existing CG model for water. The inclusion of polarizability greatly improves the reproduction of thermodynamic data measured experimentally and calculated from AL simulations for both the pure liquids and binary mixtures.