Performance of the IEF-MST solvation continuum model in a blind test prediction of hydration free energies.

The IEF-MST continuum solvation model is used to predict the hydration free energies of a set of 63 multifunctional compounds very recently compiled as a blind test (denoted SAMPL1) for computational solvation methods (Guthrie, J. P. J. Phys. Chem. B 2009, 113, 4501). Computations were performed using the IEF-MST versions parametrized at both HF/6-31G(d) and B3LYP/6-31G(d) levels. For direct comparison with other methods, computations were performed using the frozen geometries provided with the SAMPL1 data set, as well as the gas phase optimized geometries following the implementation of the IEF-MST model. Comparison with experimental data yields a root-mean square deviation for the whole set of compounds of 2.7 and 2.4 kcal/mol at both HF and B3LYP levels. The agreement between IEF-MST and experimental data is then quite remarkable, especially considering the reduced set of training compounds (72 data in water) used in the parametrization of the IEF-MST method.