Ab initiocalculation of the vibrationally resolvedO1sphotoelectron spectrum ofCO2

The oxygen $1s$ photoelectron spectrum for ${\mathrm{CO}}_2$ 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.