MCSCF (CAS) Study on Potential Surfaces of Excited States in ClCN Photodissociation

By means of MCSCF (MC9/12) method, with the polarization base set of double seta (DZP), the potential curves and surfaces of ground state and excited states ¹Π₍₁₎, ¹Π₍₂₎,¹Σ^-,¹Δ,¹Σ⁺ of linear molecule CICN and those of the excited states ^1A', ^1A" of bent molecule were calculated. The most important conclusion is that the lowest singlet excited state ¹Π₍₁₎-¹A"₍₀₎ does not cross other upper ones in photodissociation. It is point out the most possible channel in CICN photodissociation is as follows:it is through the excited state ¹Π₍₁₎-¹A"₍₀₎ that the molecule is dissociated to the fragments of ground state CN(X² Σ⁺)+Cl(²P). By calculation the experimental fact, that the distribution of rotation energy of CICN fragments is invert, is explained.