Conical intersections between X2A1 and A2B2 electronic states of NO2

► Global ab initio potential surfaces (PES) of X2A1 and A2B2 states of NO2 are computed. ► Non Adiabatic Coupling Terms (NACTs) between those states are also calculated. ► Our Beyond BO theory confirms those PESs consist general SAA CIs and RT interaction. ► Singularities of NACT on normal mode coordinates indicate the presence of CI. ► Calculated Adiabatic to Diabatic Transformation matrix show sign change for CI.