Notes. We note that the propagation method is only used for sampling geometries. For these structures, energies and forces are later calculated at the PBE-D3BJ/def2-TZVP level of theory. ⁽¹⁾A spherical wall potential is applied to ensure the structural integrity of the cluster. ⁽²⁾Interaction of P with the cluster at the distance of the cut-off radius (5.5 Å, required for binding energies). ⁽³⁾The reaction part comprises reactions in weak, medium, and high binding sites at different P-H internuclear distances (3.0–4.5 Å). ⁽⁴⁾398 structures have been removed from the training set (some distances between neighbouring atoms are larger than the selected cut-off radius).