Full dimensional quantum mechanical calculations of the reaction probability of the H + NH3 collision based on a mixed Jacobi and Radau description

Abstract

The collision between hydrogen and ammonia is a benchmark system to study chemical elementary reactions with five atoms. In this work, we present a description of the system based on mixed Jacobi and Radau coordinates combined with the time-dependent wave packet method to study the H+NH 3 reaction. The Radau coordinates are used to describe the reactive moiety NH 2 . A salient feature of this approach is that the present coordinates have the great advantage that a very small number of basis set functions can be used to describe the NH 2 group. Potential-optimized discrete variable representation basis is applied for the vibrational coordinates of the reagent NH 3 . The reaction probabilities for several initial vibrational states are presented in this paper. The role of the different vibrational excitations on the reactivity is thoroughly described.

Full-dimensional quantum dynamics study of isotope effects for the H2 + NH2/ND2/NHD and H2/D2/HD + NH2 reactions

“…Therefore, a subsystem strategy can be easily implemented to study those reactions. As have been shown in our previous papers for the reactions H+NH 3 40 and H+CH 4 41 , the nonreactive groups NH 2 and CH 3 do not change dramatically and thus can be both described using Radau coordinates, which are close to the valence internal coordinates. While the Jacobi coordinates are used only for the bond breaking and creating.…”

“…For the KEO of T N Z 1,2 , one can refer our previous papers 40,49 for more information. The T N Z 1,2 contains three parts,T…”

Advances and New Challenges to Bimolecular Reaction Dynamics Theory

“…The spectator moiety can be efficiently described by Radau vectors so that a smaller potential optimized discrete variable representation basis is sufficient for its vibration. This approach has been employed in full-dimensional calculations of initial state selected reaction probabilities for the H + NH 3 → H 2 + NH 2 (9D) and the H + CH 4 → H 2 + CH 3 (12D) reactions . For the former case, this efficient coordinate system reduces the size of the basis set by more than 85% when compared to a previous study of the same reaction with Jacobi coordinates. Theoretical studies become a necessity for gaining insight into reaction dynamics and to ultimately control chemical reactivity, by offering intimate details of the chemical dynamics and by providing intuitive mechanistic models.…”

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

“…The potential energy surface (PES) employed in the dynamics calculations was developed by Li and Guo by fitting ∼100,000 high-level ab initio points with the permutation invariant polynomial-neural network method . This PES has been used to study mode-specific dynamics of H 2 + NH 2 → H + NH 3 and its reverse reaction − and the photodetachment of H – (NH 3 ) and NH 4 – , and the obtained photoelectron spectrum is in excellent agreement with the experimental result . Dynamic and kinetic studies have also been carried out on an earlier PES using reduced- and full-dimensional quantum methods. − Undoubtedly, these quantum dynamics studies all assumed that only one bond is broken in the reaction process.…”