Electron Nuclear Dynamics of H⁺ + C₂H₂ at E_Lab = 30, 200, and 450 eV

Area of Science:

• Chemical Physics
• Computational Chemistry
• Quantum Dynamics

Background:

• Proton-molecule reactions are crucial in astrophysics and relevant to cancer therapy.
• Accurate theoretical modeling of these reactions is computationally challenging.
• Simplest-Level Electron Nuclear Dynamics (SLEND) offers a computationally feasible approach.

Purpose of the Study:

• To perform a complete SLEND investigation of the H+ + C2H2 reaction at various collision energies.
• To analyze reaction mechanisms, including scattering and fragmentation pathways.
• To compare theoretical predictions with experimental data for integral and differential cross sections.

Main Methods:

• Utilized the SLEND method, a time-dependent, variational, direct, and nonadiabatic approach.
• Employed classical mechanics for nuclei and a Thouless single-determinantal wave function for electrons.
• Performed simulations using the PACE code with the OED/ERD atomic integrals package and a 6-31G** basis set.

Main Results:

• Predicted one simple scattering and three reactive processes at 30 eV: substitution and two fragmentation pathways.
• Observed primary and secondary rainbow scattering features varying with orientation and energy.
• Achieved good agreement with experimental integral and differential cross sections for 1-electron-transfer.
• Demonstrated excellent agreement for primary rainbow scattering signatures in both 0- and 1-electron-transfer differential cross sections.

Conclusions:

• SLEND provides accurate predictions for H+ + C2H2 collisions, validating its applicability.
• The method successfully reproduces experimental cross sections and reveals detailed reaction mechanisms.
• Identified identical primary rainbow scattering angles for 0- and 1-electron-transfer, offering insights into proton-molecule collisions.
• Validated a procedure for extracting primary rainbow angles from differential cross sections.