Theoretical 1Σg+ – 1Σu+ Dipole Strengths of Some Homonuclear Diatomic Molecules: Configuration Interaction

The dipole strengths of the homonuclear diatomic molecules Li₂, C₂, Be₂, N₂, and F₂ have been calculated for high‐ and low‐energy transitions of the type ${}^1{\Sigma }_g^{+}{–}^1{\Sigma }_u^{+}.$ Increasingly accurate approximations to the ground‐state wavefunction are used, including configuration interaction. A frozen‐core approximation is used for the excited state. Comparison of dipole strengths calculated from dipole‐moment and dipole‐momentum operators stresses the importance of configuration interaction to obtain agreement between these two methods. Population analysis of the C₂ and Be₂ molecular orbitals reveals an interesting analogy with the resonance transition of the Be atom in the role of ${\text{(2s)}}^2{\text{→(2p)}}^2$ nondynamical correlation.