An effective force field for molecular dynamics simulations of dimethyl sulfoxide and dimethyl sulfoxide-water mixtures

An improved model for molecular dynamics simulations of liquid dimethyl sulfoxide (DMSO), compatible with the GROMOS96 force field, is presented. The new model was parametrized to reproduce the density and heat of vaporization and showed good agreement with experimental values for a variety of other properties of the liquid. Together with the SPC and SPC/L models for water, the new parameter set was used for the simulation of DMSO-water mixtures. In accordance with experiment, strong nonideal behavior was observed for the thermodynamic and dynamic properties of the mixtures over the range of compositions investigated. For most of these properties, both the DMSO-SPC and DMSO-SPC/L model produced values in agreement with experiment. Slightly better results were obtained using the SPC/L model for water. Compared to other DMSO and DMSO-water models tested in the literature, our parameter sets were found to perform similarly or better. Finally, we studied the solvation of two lipophilic probes (neopentane and tert-butyl alcohol) in the DMSO-water mixtures. As expected, the solubility of the probes was found to increase with the mole fraction DMSO.