Solvent effects on an S_N2 reaction profile

The polarizable continuum model has been used to evaluate the solvent effects on the energetics of the Cl^-+CH₃Cl → ClCH₃+Cl^- S_N2 reaction. Both geometry relaxation and harmonic vibrational energies have been considered, applying a recent algorithm for the analytical evaluation of second energy derivatives in solution. The results at the density functional level, using a recently proposed hybrid density functional, agree well with high-level post-Hartree-Fock calculations and with experimental data.