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

Area of Science:

• Cosmology and Astrophysics
• Physical Chemistry
• Computational Physics

Background:

• Gas cooling in the early Universe depends on hydrogen deuteride (HD) abundance and excitation.
• Accurate modeling requires understanding HD formation, destruction, and excitation pathways.
• Ion-molecule reactions dominate in pristine gas, but theoretical studies are computationally intensive.

Purpose of the Study:

• To perform a state-to-state scattering study of the HD-H+ collisional system.
• To compare an exact quantum time-independent method with a new statistical method.
• To obtain reactive and inelastic rate coefficients for astrophysical applications.

Main Methods:

• Employed an exact quantum time-independent scattering approach.
• Utilized a novel, fast, and efficient statistical method for calculations.
• Calculated rate coefficients for temperatures up to 300 K.

Main Results:

• The statistical method accurately reproduces exact quantum calculations.
• The new method meets astrophysical accuracy requirements.
• Significant reduction in computational resource requirements was achieved.

Conclusions:

• The developed statistical method is a viable and efficient alternative for calculating collisional data.
• This method can provide essential data for astrophysical simulations where exact quantum calculations are infeasible.
• It supports improved modeling of early Universe gas cooling mechanisms.