Molecular Excited States and Their Dissociation Processes from MCSCF/CI Calculations

The ground states and the excited states of NH₃, CH₅⁺ and CH₆²⁺ are investigated by MCSCF/CI calculations. It is found that the A¹A₂" states and that a³A₂" states of NH₃ are dissociative Rydberg states, and that the dissociation proceses are regarded as the Rydbergization processes. The calculations indicated that the A¹A'state and the a³A'state of CH₅⁺ are the states mixed the Rydberg states with the molecular valence states, and that the A¹A₁ state and the a³A₁ states of CH₆²⁺ are completely molecular valence states. The calculations also found that the X¹A₁' state of NH₃ is a bound sstate, and that the three-center- two-clectron interaction exists in the ground states and the excited states of CH₅⁺ and CH₆²⁺. The vertical transition energies of the excited states and the singlet-triplet splitting energies are give and explained from the chemical bonds molecular orbitals.