Although the activation barrier was significantly improved with the added harmonic functions to the C-H RPF's, the energy difference between the enolate intermediate and the reactant still deviated significantly from the reference M06-2X value (Figure ). Thus, we turned our focus to adjusting the C-C repulsive potential to achieve this effect. We added LCHFs on the C-C pair RPFs testing different combination of LCHFs for C-H RPF's that best reproduced the activation barrier. Figure shows the C-C RPF (curve in green) and its step-wise modified versions as CC_X (with X=1,3,5,7,9; see Table for more details).