A comparison of the properties of 2,2,2-trifluoroethanol and 2,2,2-trifluoroethanol/water mixtures using different force fields

It is necessary to evaluate the quality of a force field by comparison with known experimental properties before it can be used with confidence in a simulation. Here, such a study is reported for pure 2,2,2-trifluoroethanol (TFE) solutions and for TFE/water mixtures at two different compositions. Six literature force fields were examined using molecular dynamics simulations. It is found that none of the currently available force fields describe all the properties of pure liquid TFE. The models of van Buren and Berendsen, Duffy and Jorgensen, and Fioroni et al. produce properties that are in reasonable agreement with experiment. The ability to adequately describe properties of TFE/water mixtures varied with the property of interest. The heat of mixing is too unfavorable for all the models. The aggregation properties of the mixtures were well described by the model of Duffy and Jorgensen at the lower composition (30% by volume of TFE), while the Fioroni et al. model performed better at higher TFE concentrations. The activity coefficient derivative from the Fioroni et al. model was in very good agreement with experiment for all compositions studied here. Consequently, the choice of the most appropriate force field will depend on the major properties of interest. (C) 2001 American Institute of Physics.