Communication: non-adiabatic coupling and resonances in the F + H2 reaction at low energies

Quantum reactive scattering calculations on accurate potential energy surfaces predict that at energies below ～5 meV, the reaction of F atoms with H(2) is dominated by the Born-Oppenheimer (BO) forbidden reaction of the spin-orbit excited F((2)P(1∕2)) atom. This non-BO dominance is amplified by low-energy resonances corresponding to quasi-bound states of the HF(v = 3, j = 3) + H product channel. Neglect of non-adiabatic coupling between the electronic states of the F atom leads to a qualitatively incorrect picture of the reaction dynamics at low energy.