Quantum and statistical state-to-state studies of cold Ar + H collisions.

In this work we present new state-to-state integral scattering cross sections and initial-state selected rate coefficients for the Ar (S) + H (XΣ, = 0,) reactive system for collision energies up to 0.1 eV (with respect to the Ar (S) + H (XΣ, = 0, = 0) channel). To the best of our knowledge, these cross sections are the first fully state resolved ones that were obtained by performing time-independent quantum mechanical and quantum statistical calculations.

Machine Learning Representations of the Three Lowest Adiabatic Electronic Potential Energy Surfaces for the ArH Reactive System.

In this work, we present Gaussian process regression machine learning representations of the three lowest coupled A' adiabatic electronic potential energy surfaces of the ArH reactive system in full dimensionality. Additionally, the nonadiabatic coupling matrix elements were calculated. These adiabatic potentials and their nonadiabatic couplings are necessary ingredients in the theoretical investigation of the nonadiabatic reaction dynamics of the Ar + H → ArH + H and Ar + H → ArH + H reactions, as well as the competing charge transfer process, Ar + H↔ Ar + H.

Benchmarking an improved statistical adiabatic channel model for competing inelastic and reactive processes.

Inelastic collisions and elementary chemical reactions proceeding through the formation and subsequent decay of an intermediate collision complex, with an associated deep well on the potential energy surface, pose a challenge for accurate fully quantum mechanical approaches, such as the close-coupling method. In this study, we report on the theoretical prediction of temperature-dependent state-to-state rate coefficients for these complex-mode processes, using a statistical quantum method. This statistical adiabatic channel model is benchmarked by a direct comparison using accurate rate coefficients from the literature for a number of systems (H + H, HD + H, SH + H, and CH + H) of interest in astrochemistry and astrophysics.

HD-H collisions: statistical and quantum state-to-state studies.

In the early Universe, the cooling mechanisms of the gas significantly rely on the HD abundance and excitation conditions. A proper modeling of its formation and destruction paths as well as its excitation by both radiative and collisional processes is then required to accurately describe the cooling mechanisms of the pristine gas. In such media, ion-molecule reactions are dominant.