The final energies of the sampled 35474 points were determined by a composite strategy: CCSD(T)-F12b/AVDZ + (MP2-F12/AVTZ - MP2-F12/AVDZ). The explicitly correlated CCSD(T)-F12b method was expected to provide a reliable description of electron correlation while the energy difference between MP2-F12/AVTZ and MP2-F12/AVDZ was computationally less expensive to recover the basis set effects beyond AVDZ for CCSD(T)-F12b. Similarly for the Cl + C2H6 reaction, the electronic energies were computed at the same composite level of theory, with additional sinorbital corrections in the reactant region being determined at the level of MRCI+Q/AVDZ. 110