Geometric Phase Effects in the H + H₂⁺ Reaction on the Lowest Triplet Ground State

To our knowledge, this is the first time geometric phase (GP) effects in the H + H₂⁺ reaction on its lowest triplet ground state with collision energies lower than 1.85 eV have been studied using the quantum wave packet method and vector potential approach. We obtained the total reaction probabilities including and not including GP (NGP) effects for J ≤ 4. Visible GP effects could be seen at the lower energy regime but are tiny at the higher one. Moreover, they are more obvious in the product rovibrational state-resolved reaction probabilities, and the relative resonance magnitudes between GP and NGP results change with product rotational state values alternatively. The main reasons are the interferences between the one- and two-transition-state (1-TS and 2-TS) reaction paths, in that at the lower energy regime, the reaction probabilities from the 2-TS pathway show peaks of comparable probabilities compared with that of the 1-TS pathway. In addition, the "out-of-phase" trend observed in the H + H₂ reaction does not exist rigorously in this system. Importantly, the visible GP effects exist in this H₃⁺ system, which makes it a very useful candidate reaction for nonadiabatic investigations in both theory and experiment.