Global diabatic potential energy surfaces of the C2H system and dynamics studies of the C(3P) + CH → C2(X1Σ + g, a3Π) + H reaction

Using 11,453 high-level ab initio energy points, the diabatic potential energy surfaces (PESs) between the 1² A' and 2² A' states of the C₂H system were successfully constructed. In the ab initio calculations, the AVQZ basis set and the multi-reference configuration interaction method were adopted. It was found that there is a conical intersection in the collinear configuration. Based on this feature, a designed function and combined with the neural network method were used to construct the diabatic PESs. In addition, the topographic characteristics of the diabatic PESs were described in detail. To further evaluate the constructed diabatic PES, the C(³P) + CH → C₂(X¹Σ + g, a³Π) + H reaction was studied using quantum method. Several dynamical results were reported and compared with previous studies. The reasonable dynamical results suggest that the diabatic PESs constructed in this paper is suitable for varieties of dynamical studies of the C₂H system.