Thus, for comparison we ran the same calculations with B3LYP and SMD, as well as M06-2X with CPCM and SMD (Figure ). As illustrated in Figure , the resulting spread of the predicted activation energy is large. The difference between the B3LYP and M06-2X barrier is as much as 9.5 and 9.2 kcal/mol with the CPCM and SMD solvation correction, respectively. This difference is surprisingly large for the small unimolecular reaction under investigation here, demonstrating the importance of awareness to functional dependencies. However, the main aim of our DFT calculations was to obtain the reaction free energy to be used for calibrating the EVB Hamiltonian, and here the variation is within the expected error of DFT calculations (Figure ).