Renner-Teller coupled-channel dynamics of the N(2D)+H2 reaction and the role of the NH2 A 2A1 electronic state

We present Renner-Teller (RT) and Born-Oppenheimer (BO) coupled-channel (CC) dynamics of the reaction N-14(D-2)+H-1(2)(X (1)Sigma(+)(g))-> NH(X (3)Sigma(-))+H(S-2), considering both NH2 coupled electronic states, X B-2(1) and A (2)A(1), and Coriolis interactions. We use the best available potential energy surfaces (PESs), and we obtain initial-state-resolved reaction probabilities, cross sections, and rate constants through the real wavepacket and flux methods, taking into account the nuclear-spin statistics for both electronic states. Contrasting RT-CC with more approximate results, we point out the role of RT and Coriolis couplings, and discuss the importance of the A (2)A(1) excited state on the initial-state-resolved dynamics and on the thermal kinetic rate. Confirming the previous results, RT couplings transfer partly the reactivity from X B-2(1) to A (2)A(1), and CC calculations are necessary to obtain accurate high-energy cross sections. When H-2 is initially rotating, RT couplings enhance strongly the electronic-state-resolved A (2)A(1) reactivity. Considering the nuclear-spin statistics for both electronic states, we find out that the A (2)A(1) state plays a significant role in the rotationally resolved dynamics of N(D-2)+ortho-H-2. However, the BO-X B-2(1) approximation gives a thermal rate that is slightly smaller than the one obtained by the RT-CC calculations. This implies that this usual approximation is acceptable to calculate unresolved kinetic data of the title reaction. Our calculated rate constant values within the 213-300 K temperature interval are in excellent agreement with the experimental ones.