Ab initio data. Top left: the potential energy curves for diabatic states U₁(R) and U₂(R) and their coupling U₁₂(R) are illustrated. Bottom left: the dipole moment of the diabatic state 2 is illustrated. Top right: the potential energy curves of the Χ¹Σ⁺ and A¹Π states within the BO approximation. Bottom right: the Χ¹Σ⁺ permanent dipole-moment and A¹Π → Χ¹Σ⁺ transition dipole-moment functions. All the data were taken from Giese & York (2004) and Zeiri & Balint-Kurti (1983).