Dynamics studies for the C(3P) + H2 reaction: Based on new global diabatic potential energy surfaces

The diabatic potential energy surfaces (PESs) for the 13A″ and 23A″ states of the CH2 system were constructed using a neural network approach combined with a constraint function. The ab initio calculations were performed at the MRCI-F12 level of theory with the AVQZ basis set. In addition, the topographical features of the PESs are discussed in detail, and it is demonstrated that the newly constructed diabatic PESs can accurately reproduce nonadiabatic processes between electronic states. To elucidate the influence of nonadiabatic effects, adiabatic and nonadiabatic dynamics for the C(3P) + H2(v = 0, j = 0) reaction were investigated using the time-dependent wave packet method on the new PESs. A mechanistic discussion of the nonadiabatic effects is presented, based on a comparison between the adiabatic and nonadiabatic results. It was found that the adiabatic results underestimate the actual values due to the neglect of the nonadiabatic effects. This collectively demonstrates that nonadiabatic effects play a critical and non-negligible role in the reaction dynamics.