Quantum State-to-State Dynamics of the H + LiH → H₂ + Li Reaction

Abstract

State-to-state quantum dynamics calculations for the H + LiH (v = 0-1, j = 0) → H2 + Li reactions are performed based on an ab initio ground electronic state potential energy surface (PES). Total and product state-resolved integral and differential cross sections and rate constants are calculated. The present total integral cross sections and rate constants for the H + LiH (v = 0, j = 0) reaction are found to be in agreement with previous literature results. Product state-resolved integral cross sections and rate constants reveal that the H2 products are preferred to be formed in their rovibrational excited states. The differential cross sections show that the intensity of forward scattering for the H2 products in their rovibrational excited states is stronger than other states. The mechanisms for the v = 0 and v = 1 reactions are found to be highly consistent with each other. Further, the influence of the stripping mechanism on the H + LiH reaction is studied. It is found that the stripping mechanism could be responsible for the decrease of the reactivity, the product state distribution, and scattering direction of the H2 products. It is related to the "attractive" feature of the underlying PES.

Theoretical Study of the Energy Disposal Mechanism and the State-Resolved Quantum Dynamics of the H + LiH+ → H2 + Li+ Reaction

“…Such differences may arise due to the difference between the exoergicity of the two reactions as the neutral reaction is less exoergic (Δ E ≈ −2.258 eV) than the present ionic reaction. For lower v ′ levels, products are rotationally excited, and for higher v ′ levels, products are rotationally cold akin to the j ′ distributions for the neutral counterpart of the reaction R1 . Similar observations are also reported under cold and ultracold conditions by Roy and Mahapatra .…”

“…Similar observations can be made for LiH + ( v = 1, j = 0) and LiH + ( v = 0, j = 1), for which the product rotational level resolved state-to-state ICSs are shown in Figures S4 and S5. The above observation is in contrast to the neutral H + LiH → H 2 + Li reaction where a broad range of j ′ distribution has been found . Such differences may arise due to the difference between the exoergicity of the two reactions as the neutral reaction is less exoergic (Δ E ≈ −2.258 eV) than the present ionic reaction.…”

“…The collisions of a H atom and a H + ion with the LiH molecule and its cationic counterpart LiH + are believed to be important in primordial lithium chemistry. − These collisions are also considered to play a significant role in the cooling process of the early universe during its evolution. As a result, the chemistry of LiH 2 and LiH 2 + has received a great deal of attention in the past two decades. − ,− According to the study of Bodo et al, the H + LiH + → H 2 + Li + reaction is one of the depletion processes for the LiH + ion along with the collision induced dissociation (CID). However, the other two channels, viz., hydrogen exchange and non-reactive, are responsible for the survival of the ionic LiH + species.…”

A Quantum Mechanical Study of the k–j and k′–j′ Vector Correlations for the H + LiH → Li + H2 Reaction

“…Under these circumstances, the relative importance of the largest values of J gets smaller. Results presented in Figure are in good accordance with the mechanistic analysis of the H + LiH reaction performed by He et al for rotationless reactants; in the range of collision energies studied, up to 0.6 eV, the authors found the collisions to be dominated by a stripping mechanism giving rise to forward scattering and corresponding to medium and large values of J .…”

“…Compared to scalar observables, and exceptions notwithstanding, ,,, the mechanism of reaction and the vectorial observables more directly connected to it have received little attention. However, it is possible to extract an overall picture of the mechanism behind the H + LiH reactive collisions from the studies already available in the literature.…”