Study on the kinetics and dynamics of the H₂ + NH₂⁻ reaction on a high-level ab initio potential energy surface

Abstract

Gas-phase ion-molecule reactions play major roles in many fields of chemistry and physics. The reaction of amino radical anion with hydrogen molecule is one of the simplest proton transfer reactions...

Validating experiments for the reaction H2 + NH2− by dynamical calculations on an accurate full-dimensional potential energy surface

“…11 The rate coefficients on the FI-NN PES were slightly higher than the experimental values. 11 The FI-NN PES did not include the NH 4 À channel and the description of the long-range part was not sufficiently accurate. Furthermore, in order to provide reliable estimation for the vertical detachment energy (VDE) of the PC and NH 4 À anions, additional diffuse basis functions were suggested to be included, 26 but were not included in the FI-NN PES.…”

“…The available theoretical and experimental results 1,4,7,11 are also shown for comparison. The experimental results measured by Otto et al showed a negative dependence between 20 and 300 K and a positive dependence from 8 to 20 K. 1,11 Similarly, QCT calculated thermal rate coefficients on this new PIP-NN PES show an inverse temperature dependence from 50 to 300 K. However, they are higher than the experimental values. In order to partly remedy the ZPE leakage issue in the QCT, 54 the hard ZPE constraint method was employed.…”

“…Only a few relevant investigations, by theory or experiments, have been reported. 1,4,[7][8][9][10][11] Bohme et al measured the rate coefficients of (R1) independently in forward (k f ) and reverse (k r ) directions, and the equilibrium constant (K eq ) at 297 K in a flowing afterglow system. The corresponding rate coefficients were k f = (2.3 AE 0.5) Â 10 À11 and k r = (9.2 AE 1.8) Â 10 À13 cm 3 molecule À1 s À1 , and the ratio of the rate coefficients was in good agreement with the equilibrium constant.…”

“…As the temperature decreases, k f increases until a maximum at 20 K. From 20 to 8 K, k f was found to decrease again. 1 Theoretical studies 1,4,[8][9][10][11] are useful to confirm the reaction profile of (R1). As shown in Fig.…”

“…11 The fundamental invariant neural network (FI-NN) method 33 was used for fitting and the resulting PES is denoted as FI-NN PES hereafter. 11 The rate coefficients on the FI-NN PES were slightly higher than the experimental values. 11 The FI-NN PES did not include the NH 4 À channel and the description of the long-range part was not sufficiently accurate.…”