Quantum infinite order sudden approximation for ion-molecule reactions: Treatment of the He + H2+ system

Abstract

In this work the ion-molecule reaction He + HZ+ (u,) -+ HeH' (u,) + H (u, = 0-7, uf = 0-2) was studied quantum mechanically in the energy range 1.3 eV 5 El,, c: 1.8 eV. The calculations were carried out employing the Reactive Infinite Order Sudden Approximation (RIOSA). The two features characteristic of this system in the above energy range, namely the strong enhancement of the reaction rate with the initial vibrational energy (at a fixed total energy) and the relatively weak dependence of the cross sections on translational energy, were found to be well reproduced in the numerical treatment. The results also revealed the existence of two mechanisms of the exchange process: one is the ordinary mechanism and the other is probably related to the spectator stripping model.

Beyond Born-Oppenheimer Treatment for Multi-State Photoelectron Spectra, Phase Transitions of Solids and Scattering Processes

“…7.2 HeH + 2 : Four Electronic State SHS Over the last several decades the prototype proton transfer reaction He + H + 2 → HeH + + H has received a lot of attention as a test case for an endothermic reaction where the product formation can be enhanced more effectively by vibrational rather than translational energy. 202,203 Although dynamics performed over the past few decades on different PESs for the system was able to observe the vibrational enhance-ment for the ground He+H + 2 → HeH + + H reaction [204][205][206] , the computed cross section are not yet fully aligned with the experimental observations 202,203,[206][207][208][209][210][211][212][213] . Indeed, existence of CIs between the lowest electronic states of the HeH + 2 system [214][215][216] necessitates the inclusion of excited states for an accurate description of the proton transfer He+H + 2 → HeH + + H reaction as well as excited state hydrogen transfer reaction He + +H 2 → HeH + + H.…”

“…112 The CI between the other electronic states can be found in detail in Ref 112. Once the adiabatic PESs and NACTS are obtained, we employed first principle based BBO theory to construct global multistate diabatic potential matrix of the lowest four states of this system and finally, those are engaged to perform multistate quantum dynamical calculation using the FCC TDWP approach to probe the proton transfer reaction He+H + 2 → HeH + + H. 112 Reaction probabilities for total angular momentum J=0-45 are calculated over the energy range 0.9 -1.4 eV and subsequently, we utilized those quantities to calculate the state-to-state as well as total integral cross section, which is presented in Figure 25 in comparison with other theoretical [210][211][212][213]217 and experimental results 202,203,[206][207][208][209] .…”

The Electronic Non-Adiabatic Coupling Matrix: A Numerical Study of the Curl Condition and the Quantization Condition Employing the Mathieu Equation

“…We recently pointed out that the appropriate theoretical approach to handle the singularities in molecular physics is similar to approaches within field theory and elementary particles. [13][14][15][16] Because the singular NACTs appear in the nuclear adiabatic BO-SEs, these equations cannot be solved unless the singularities are eliminated rigorously. [17][18][19][20] In ref 17, where this issue was discussed for the first time, it was revealed that a necessary condition for being able to eliminate the NACTs from the BO-SE is the fulfillment of a Curl condition (to be discussed in section II; see eq 4).…”

Oscillating reactivity of the light atom transfer reaction chlorine atom + hydrogen chloride .fwdarw. chlorine hydrogen + chlorine atom: dependence on the nature of the potential energy surface

“…In this paper we report on quantum mechanical results regarding two of the most important ion-molecule reactions, namely He + H2+(Ui) -HeH+ + H (ref 7,8) (I) (Ar + H2)+ -ArH+ + H (ref 9) (II)…”