The energy barrier corresponding to these three representative substituents can obtain the linear free energy relationship 11 for S1 and S2 respectively(Fig. ). For the reaction of S2, the linear free energy relationship obtained by theoretical calculation and the experimental research result (rich The electron region ρ=4.5, the slope of the electron-deficient region is negative), and it can be found that there is still a large difference between the two. In order to determine the effect of computational level on the reproducible of linear free energy relationship, we selected a concerted aromatic nucleophilic substitution reaction recently reported by Ritter et al 12 . Based on the reaction mechanism proposed by the author, we calculated the linear free energy relationship of this reaction at the same calculation level as before and compared it with the experimentally measured linear free energy relationship. Although the IRC also confirms the concerted mechanism of this reaction, the obtained ρ value is larger compared with the experimental results which reflects the insufficient of existing theoretical methods for the calculation of the linear free energy relationship(Fig. ). We proposed that this systematic error may be derived from the error of the existing implicit solvation model which has been reported that may play a important role 13 .