Theoretical study of the valence photoelectron spectrum of ozone: An analysis of correlation effects and configuration interaction (CI) model spaces

Abstract

Minimal basis set CI calculations with different configuration spaces including full CI are compared for the ground and ionized states of O3. A double inversion with respect to the Koopmans Theorem (KT) ordering is found, and the inadequacy of approaches based on a single configuration reference is pointed out. The strong correlation effects appear to be well described in terms of fluctuations within a quasidegenerate set comprising the three π orbitals, giving a picture of O3 as a quasi-open-shell system. Extended 2h–1p schemes based on the quasidegenerate model give good reproduction of the FCI results. Extension to the whole valence region gives indication of a further shattering of the intensity over the simple 2h–1p results. An assignment for the complete valence spectrum is proposed.