Nonadiabatic dynamics on the two coupled electronic PESs: the H+ + O2 system

Area of Science:

• Chemical Physics
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Accurate potential energy surfaces (PESs) are crucial for understanding ion-molecule collisions.
• Previous theoretical studies of H+ + O2 collisions had limitations in describing nonadiabatic effects.

Purpose of the Study:

• To compute multistate adiabatic and diabatic PESs for the H+ + O2 system.
• To calculate interaction potentials and nonadiabatic coupling matrix elements.
• To perform quantum dynamics calculations for specific collision processes.

Main Methods:

• Employed Jacobi coordinates, cc-pVTZ basis set, and ic-MRCI level of theory.
• Utilized a multistate diabatic potential matrix and the VCC-RIOSA scheme for quantum dynamics.
• Computed scattering quantities at collision energies of 9.5 and 23 eV.

Main Results:

• Generated accurate PESs and nonadiabatic coupling elements for the H+ + O2 system.
• Quantum dynamics calculations showed improved agreement with experimental results for IVE and VCT processes.
• Differences from previous studies were attributed to advanced diabatization methods and theoretical levels.

Conclusions:

• The refined PESs and dynamics calculations provide a better theoretical description of H+ + O2 collisions.
• Further improvements are possible with modifications to ab initio PESs and interaction potentials.
• The study offers valuable insights into the reaction mechanisms of vibrational charge transfer and inelastic scattering.