Non-adiabatic coupling in the potential energy surfaces of SO2 molecule

Abstract

To investigate the potential energy surfaces and the coupling between the adiabatic states of SO₂ 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 ¹A₁ and 1 ¹B₂ states (the A′ states in C_s symmetry) and 1 ¹A₂ and 1 ¹B₁ states (the A′′ states in C_s symmetry) using NACTs and adiabatic-to-diabatic transformation (ADT) angles. Our results confirm reasonable interaction between 1 ¹A₁ and 1 ¹B₂ states and strong interaction between 1 ¹A₂ and 1 ¹B₁ states.