ON THE THEORETICAL DETERMINATION OF THE ELECTRON-AFFINITY OF OZONE

Multiconfigurational electron correlation methods have been analyzed i n order to theoretically compute the electron affinity (EA) of ozone. The near-degeneracy correlation effects, which are so important in O3 and O3-, have been described using complete active space (CAS) SCF wav e functions. Remaining dynamic correlation effects are computed using second-order perturbation theory (the CASPT2 method). The best calcula ted adiabatic value (including zero-point energy corrections), 2.19 eV , is about 0.09 eV larger than the experimental value. Comparative stu dies using size-consistent coupled pair functional approaches (CPF and ACPF) have also been performed. The harmonic frequencies in O3- have been determined to be: omega1 = 992, omega2 = 572, and omega3 = 879 cm -1, which gives a zero-point energy of 0.151 eV.