to the chemical accuracy (~1 kcal mol -1 ). The largest differences appear in the respective exit channels. An additional test of quality of PES-2024 was performed considering points outside of the points used in the fitting. So, based on independent scans of points for the R1 and R2 paths (Figure ), 10 randomly scattered geometries for each path were selected, including attractive and repulsive zones, which correspond to energies in the range of ~40 kcal mol -1 . Now the RMSEs are larger, 1.53 and 2.75 kcal mol -1 , respectively, for the R1 and R2 paths. Note, however, that the largest errors appear in repulsive zones, with energies about 35 kcal mol -1 . We assume that during the reactive process, from reactants to products, with very low barriers, these repulsive zones will be scarcely visited and therefore will have little influence on the dynamics of the reaction.