Wave packet calculations for H2(v1=10–14)+H2(v2=0–2): Reaction and dissociation mechanisms

Abstract

A restricted dimensionality quasiclassical trajectory study of H 2 (v,0)+ H 2 (v ′ ,0) Four mathematical dimensional quantum mechanical studies of tetra-atom systems: State-to-state J=0 probabilities for the H 2 +OH→H 2 O+H reaction Collision induced dissociation and four center exchange reaction in H 2 (v 1 ϭhigh)ϩH 2 (v 2 ϭlow) are studied by means of time-dependent wave packet calculations and within a three-degree-of-freedom reduced dimensionality model. The role of both-vibrationally excited and vibrationally cold-collision partners is examined varying v 1 between 10 and 14 and v 2 between 0 and 2, respectively. From the analysis of the results, a clear picture of the main mechanisms of dissociation and reaction has been obtained, and the regions of the potential energy surface most sensitive to the dynamics have been identified. In this way, reaction bottlenecks are found to significantly depend on the initial v 1 state, owing to the anharmonicity of these v 1 states near dissociation and the different regions of the potential explored by the associated wave packets. The topography of such bottlenecks provide a basis for the existence of tunneling in ͑v 1 ϭ10,12, v 2 ϭ0 -2͒ reactions. Regarding the dissociation process, we find that there are two main mechanisms for dissociation; one where the unbroken diatom recoils with respect to dissociated fragments, and the second, where the diatom passes through the dissociated fragments. These mechanisms are responsible of a double peak observed in some dissociation probabilities. For ͑v 1 ϭ14, v 2 ϭ0 -2͒ reagents, new processes appear with non-negligible probabilities: ͑i͒ inelastic collision by insertion of the cold diatom into the vibrationally excited one and ͑ii͒ dissociation of the initially cold diatom. These features, together with the observation of structures in all channel probabilities, suggest that four-atom complexes are formed during collision.

Fully converged integral cross sections of collision induced dissociation, four-center, and single exchange reactions, and accuracy of the centrifugal sudden approximation in H2 + D2 reaction

“…[30][31][32][33][34][35][36][37][38] and reduced dimensional quantum mechanical (QM) methods. 29,[39][40][41][42][43][44] Lu et al 45 carried out the first accurate full-dimensional QM calculations of the H 2 + H 2 reaction using the time-dependent wave packet method. In their study, initial state selected total reaction probabilities for the three competitive processes were reported with total angular momentum J = 0, and the effect of reagent vibration on reactions was examined on the ASP PES.…”

Full-dimensional quantum wave packet study of rotationally inelastic transitions in H2+H2 collision

“…It can also be modified to study reactive scattering, an important aspect of dynamics that has attracted some recent theoretical attention. [67][68][69][70] Numerically, such full-dimensional quantum approach will provide important benchmarks for more approximate quantum 67,68 and semiclassical 18,19,22,69,70 descriptions of the dynamics.…”

Energy transfer and dissociation in H2+H2: The role of internal energy of the collider

“…Fig. 4g for collider H 2 (0, 8) shows that changes in its vibrational energy at low translational energy are accompanied by corresponding changes in the internal energy of the collider. When vibrational relaxation of the target occurs at higher translational energy, more energy goes into both rotational and vibrational modes of the collider than in the case of the reference collisions.…”

“…In the restricted dimensionality quantum and classical study of H 2 + H 2 by di Domineco et al [8], they reached the conclusion that energy transfer from the collider has a minor effect. In later work of the same group [9], they stated that examination of the role of internal energy in promoting collision induced dissociation is needed before embarking on studies in which the collider is treated as a pseudo-atom with its internal degrees of freedom regarded as unimportant.…”