Reaction free energies in organic solvents: comparing different quantum mechanical methods.

A variety of quantum mechanical (QM) methods, basis sets and solute cavity descriptions using the conductor-like polarisable continuum model for the modelling of reaction free energies in solution have been evaluated and compared. In order to test the performance of each QM level of theory and cavity model, five common types of organic reactions in different solvents have been considered. The study shows that the hybrid metageneralised-gradient approximation M05-2X functional, in conjunction with the MG3S basis set and UA0 or universal force field cavities, produces results in the best overall agreement with experimental data. In addition, within the UA0 formalism, explicit cavities should be built on the hydrogen atoms that undergo transformation during chemical reaction. [ABSTRACT FROM AUTHOR]