Ab initio calculation of the vibrationally resolved O 1s photoelectron spectrum of CO₂

The oxygen 1s photoelectron spectrum for CO₂ has been calculated using ab initio electronic structure theory, a localized hole simulated by the equivalent-cores approximation, and the harmonic-oscillator approximation. The predicted spectrum is found to be in good agreement with a recently reported experimental spectrum, and is in better agreement with the experimental spectrum than is an earlier prediction by Domcke and Cederbaum. The equivalence of the approach taken here and that used by Cederbaum and Domcke is discussed, as well as the reasons for the differences in the calculated results.