Quantum and quasiclassical dynamics of the multi-channel H + H2S reaction

Differential Cross Sections for the H + H2S → H2 + SH Reaction: A Full-Dimensional State-to-State Quantum Dynamics Study

We utilized the time-dependent wave packet approach to compute the first full-dimensional (6D) state-to-state differential cross sections (DCSs) for the title reaction with the initial nonrotating H2S in the ground and the (100) and (001) vibrational excited states. It is found that the fundamental symmetric and asymmetric stretching excitations of H2S exhibit almost the same influence on the DCS, but unlike the H + H2O → H2 + OH reaction, they greatly increase the vibrational excitation of both the H2 and SH products. The hot vibrational state distributions of H2 are consistent with the prediction of product energy disposal by Polanyi's rules for an early barrier reaction. Because the incident H atom reacts strongly with both the ground and excited S-H states, the large populations of product SH(v2 = 1), which are very close to the relative reactivity of the initial S-H(v = 0) state, can still be explained by the local mode picture for H2S and the nonreacting SH bond's spectator nature.

Toward a Comprehensive Understanding of Mode-Specific Dynamics of Polyatomic Reactions: A Full-Dimensional Quantum Dynamics Study of the H + NH3 Reaction

Mode specificity not only sheds light on reaction dynamics but also opens the door for chemical reaction control. This work reports a state-of-the-art full-dimensional quantum dynamics study on the prototypical hydrogen abstraction reaction of hydrogen with ammonia, which serves as a benchmark for advancing our fundamental understanding of polyatomic reaction dynamics. By taking advantage of the (3 + 1) Radau-Jacobi coordinates, the bond-specific probabilities are resolved with the reactant NH₃ initiated from either a non-degenerate or degenerate stretching vibrational state. The observed different atom-specific abstraction probabilities from individual states of the degenerate pair are rationalized in the local mode representation according to the different vibrational energy deposited in each N-H bond. It is verified that the three H atoms in NH₃ have the same abstraction probability as that from the degenerate pair and the linear combination of the degenerate pair gives the same reaction probability. In addition, the symmetric and asymmetric stretching modes of the reactant NH₃ have comparable efficacies on driving the reaction.

Mode- and Bond-Selected Reaction of H with Local Mode Molecule HDS

Understanding mode- and bond-selected dynamics of elementary chemical reactions is of central importance in molecular reaction dynamics. The initial state-selected time-dependent wave packet method is employed to study the mode and bond selectivity, isotopic branching ratio, and temperature dependence of rate constants of the two-channel reaction of H with local mode molecule HDS. For the abstraction channel, fundamental excitation of the HS (DS) bond of the reactant HDS significantly enhances the H-abstraction (D-abstraction) reaction, whose efficacy is higher than the same amount of translational energy except at low energies just above the energy threshold. This is in sharp contrast to the prediction of Polanyi rules: translational energy is more efficient than vibrational energy in enhancing a reaction with an early barrier. The recent sudden vector projection model is then applied to rationalize the observed mode specificity, which, however, shows that the translational mode vector has a larger coupling with the reaction coordinate than the stretching vector of the active bond, implying a reversed relative efficacy on promoting the reaction as well. In contrast, the mode and bond specificity for the exchange channel is not as strong as for the abstraction channel due to the regulation of the shallow well along the reaction path.

Mode-specific quantum dynamics and kinetics of the hydrogen abstraction reaction OH + H2O → H2O + OH

The synergistic effect between the reactant stretching and bending modes on promoting the reaction.

Spiers Memorial Lecture : Introductory lecture: quantum dynamics of chemical reactions

This Spiers Memorial Lecture discusses quantum effects that can be calculated and observed in the chemical reactions of small molecules.

Dynamics and kinetics of the reaction OH + H2S → H2O + SH on an accurate potential energy surface

Mode specificity and product energy disposal are unveiled in the reaction OH + H₂S → H₂O + SH.

3D time-dependent wave-packet approach in hyperspherical coordinates for the H + O2 reaction on the CHIPR and DMBE IV potential energy surfaces

3D wavepacket quantum dynamics methodology ICS calculation of H + O₂ reaction on the CHIPR and DMBE IV PESs by J-shifting scheme.

Recent advances in quantum scattering calculations on polyatomic bimolecular reactions

This review surveys quantum scattering calculations on chemical reactions of polyatomic molecules in the gas phase published in the last ten years.

Quasi-classical trajectory studies on the full-dimensional accurate potential energy surface for the OH + H2O = H2O + OH reaction

The first accurate PES for the OH + H₂O reaction is developed by using the permutation invariant polynomial-neural network method to fit ∼48 000 CCSD(T)-F12a/AVTZ calculated points.