Auger decay of the $\mathrm{C}1s\to 2{\pi }^{*}$ excitation of CO

Calculations on the Auger decay of CO after the $\mathrm{C}1s\to 2{\pi }^{*}$ excitation have been performed utilizing a multichannel Schwinger approach. The bound orbitals used to expand the multichannel configuration-interaction wave functions of the ion state were the natural orbitals of a single excitation and double excitation configuration-interaction (CI) calculation on the $\mathrm{C}{1s}^{-1}$ core-hole state of CO. Fixed-nuclei photoionization cross sections were then obtained with target states represented by complete active space CI wave functions. An analysis of the resulting cross sections using Fano’s spectral line profile and the lifetime vibrational interference theory has lead to photoabsorption profiles in good agreement with experimental measurements. Additionally, we have found good agreement with experimental data for the resulting photoelectron and photoemission spectra.