SEMIEMPIRICAL CALCULATIONS OF SINGLET-TRIPLET AND TRIPLET-TRIPLET TRANSITIONS

Semiempirical calculations of the PPP-type with optimum values of parameters (γμμ=8.2 eV, βc=-2.5 eV) reproduce fairly well the singlet-triplet (S-T) and triplet-triplet (T-T) excitation energies and oscillator strengths with conjugated hydrocarbons of various structural types. The usefulness of this parametrization is shown with anthracene. Moreover, the applicability of the Hückel's N→V1 energies for estimates of the S-T transitions is mentioned. © 1969 Springer-Verlag.