The impact of non-adiabatic effects on reaction dynamics: a study based on the adiabatic and non-adiabatic potential energy surfaces of CaH

• Published in: Physical chemistry chemical physics : PCCP 2023-08, Vol.25 (34), p.22744-22754
• Main Authors: He, Di, Li, Wentao, Li, Quanjiang, Chen, Shenghui, Wang, Li, Liu, Yanli, Wang, Meishan
• Format: Article
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp02416d

The two-state non-adiabatic potential energy matrices of the CaH 2 + system are calculated via a diabatization approach by using a neural network model. Subsequently, the adiabatic and non-adiabatic potential energy surfaces (PESs) are constructed based on these non-adiabatic potential energy matrices. Furthermore, based on the adiabatic and non-adiabatic PESs, the Ca + (4s 2 S) + H 2 (X 1 Σ + g ) → H( 2 S) + CaH + (X 1 Σ + ) reaction is studied using the time-dependent wave packet method. Comparative analysis of the experimental and theoretical integral reaction cross-sections (ICSs) indicates that the maximum deviation between the results obtained from the adiabatic PES and the corresponding experimental value is 12.7 bohr 2 ; in contrast, the maximum discrepancy between the theoretical result derived from the non-adiabatic PES and the experimental value is merely 0.42 bohr 2 . The potential well along the reaction path acts as a 'filter', selectively guiding intermediates with longer lifetimes in the potential well back to the reactant channel. This phenomenon indicates that the non-adiabatic effects significantly influence the reaction dynamics of the CaH 2 + system. The crossover point is precisely situated within the potential well of the first excited state of the CaH 2 + system, causing the majority of intermediates within the well to return back to the reactant channel.