Diabatic Potential Energy Surfaces for the CaH₂ System and Dynamics Studies for the Ca(¹S) + H₂ Reaction

Area of Science:

• Chemical Physics
• Quantum Chemistry
• Computational Chemistry

Background:

• The reaction between Calcium (Ca) and Hydrogen (H2) is a fundamental process in chemical dynamics.
• Understanding nonadiabatic effects is essential for accurately modeling chemical reactions involving multiple electronic states.

Purpose of the Study:

• To construct global diabatic potential energy surfaces (PESs) for the CaH2 system.
• To investigate the influence of nonadiabatic effects on the Ca + H2 reaction dynamics.

Main Methods:

• Neural network methods were employed to construct diabatic potential energy surfaces (PESs).
• Time-dependent wave packet method was used for both adiabatic and nonadiabatic dynamical calculations.
• Comparison with previous theoretical results was performed.

Main Results:

• Two crossing points were identified between the 1¹A' and 2¹A' states of CaH2.
• Newly constructed diabatic PESs accurately describe nonadiabatic processes.
• Adiabatic calculations neglecting the Ca(¹P) + H2 channel yielded significantly different results compared to nonadiabatic calculations.

Conclusions:

• Nonadiabatic effects play a critical role in the Ca + H2 reaction dynamics.
• The developed diabatic PESs provide a reliable description of nonadiabatic processes.
• Accurate modeling of this reaction requires the inclusion of nonadiabatic effects.