Molecular orbital study of the ground and excited states of ozone

Abstract

Molecular orbital results obtained by the self-consistent-field Xα scattered wave (SCF-Xα-SW) method employing overlapping spheres are presented for the ground state and 15 excited states of ozone (O3). The results are compared with those of ab initio calculations which used the Hartree–Fock (HF), the generalized valence bond (GVB), and GVB with configuration interaction (CI) methods. The Xα–SW method yields the correct gound state (1A1) as do the GVB and GVB–CI methods which explicitly include electronic correlation effects. This is in contrast to the HF method, which predicts the ground state to be a 3B2 state. The Xα–SW molecular orbital (MO) results for the lower, dominantly covalent electronic states considered represent a substantial improvement over the HF–MO results and are consistent with the accurate GVB and GVB–CI results. The results are much less satisfactory for the higher states which are more ionic in character.