Since the ∆H r calculation is based on TCIT and can be performed in an on-the-fly manner, to this point, the activation energies of all four classes of reactions can be predicted quickly and accurately. As an outcome, complete reaction networks can be generated for arbitrary alkanes. A pyrolysis network of propane containing 28 reactions and 11 products is provided as an example (Fig. ). All possible unimolecular decomposition and bimolecular reactions that may yield no larger than C3 products were included.