We present a quantum chemistry (QM)-based method that computes the relative energies of intermediates in the Heck reaction that relate to the regioselective reaction outcome: branched (α), linear (β), or a mix of the two (Figure ). The calculations are done for two different reaction pathways (neutral and cationic) and are based on r 2 SCAN-3c single point calculations on GFN2-xTB geometries that, in turn, derive from a GFNFF-xTB conformational search. The method is completely automated and is sufficiently efficient to allow for the calculation on thousands of reaction outcomes.