Dear "Parameter-Gurus", I used the (Jan '04) TFE parameters kindly provided by Alex M. for simulation of a 80% (v/v) TFE/water-mixture. There seem to be too little TFE-TFE interactions/H-bonds as compared to experimental data(e.g. J.Phys.Chem. A 2005, 109, 7667-7676) probably resulting from wrong F-atom parameters. Is anybody working on a new optimization of CHarmm TFE parameters ? Maybe I could join this effort based on our experiences with different boxes @ various TFE/water ratios (e.g. 4%, 20%, 40%, 60%, 14%, 30% and 80%[v/v]) mixtures. best regards, David