Non-adiabatic coupling in the potential energy surfaces of SO molecule.

To investigate the potential energy surfaces and the coupling between the adiabatic states of SO molecules, it is necessary to consider the non-adiabatic coupling terms (NACTs), where the Born-Oppenheimer approximation breaks down. In this work, we analyze the conical intersections between 1 A and 1 B states (the A' states in symmetry) and 1 A and 1 B states (the A'' states in symmetry) using NACTs and adiabatic-to-diabatic transformation (ADT) angles. Our results confirm reasonable interaction between 1 A and 1 B states and strong interaction between 1 A and 1 B states.