Electronic structure and vertical excitation spectrum of methylene amidogen CH₂N

Ab initio electronic structure calculations are reported for five electronic states of the methylene amidogen radical. Structure parameters for the ground electronic state are predicted by RHF and D ‐ MBPT (4) calculations. Vertical excitation energies were determined using four different theoretical chemical models: complete active space ( CAS ) MCSCF , CAS / MCSCF plus singles and doubles Cl, fourth‐order many‐body perturbation theory SDQ ‐ MBPT (4), and coupled‐cluster theory.