Comparison of various quantum chemistry methods for the computation of equilibrium constants

Ab initio as well as density functional computations have been carried out to test their ability to reproduce experimental equilibrium constants. Three kinds of equilibriums in the gaseous phase have been studied: equilibriums involving nitrogenized compounds or methanol or chlorinated compounds. The basis set effect is also examined. In this work, we show that hybrid HF-DFT and G2 methods seem to be the best adapted to compute this thermodynamic parameter.