A TransitionState Resonance Radically Reshapes AngularDistributions of the <i>F</i> + <i>H</i>₂ → <i>FH</i>(<i>v</i>_f = 3)+ <i>H</i> Reaction in the 62–102 meV Energy Range

Reactive angular distributions of the benchmark <i>F</i> + <i>H</i>₂(<i>v</i>_i = 0) → <i>FH</i>(<i>v</i>_f = 3) + <i>H</i> reaction show unusual propensity toward small scattering angles, a subject of a long debate in the literature. We use Regge trajectories to quantify the resonance contributions to state-to-state differential cross sections. Conversion to complex energy poles allows us to attribute the effect almost exclusively to a transition state resonance, long known to exist in the <i>F</i> + <i>H</i>₂ system and its isotopic variant <i>F</i> + <i>HD</i>. For our detailed analysis of angular scattering we employ the package DCS_Regge, recently developed for the purpose [Akhmatskaya, E.; Sokolovski, D. Comput. Phys. Commun. 2022, 277, 108370].