Influence of the channel interaction on the photoabsorption and photoionization spectra of carbon dioxide

The integral and the differential photoionization cross sections of carbon dioxide are computed in the random-phase approximation coupled with a K-matrix based technique. The use of special polynomial spherical Gaussian-type orbitals provides an adequate representation of the electronic continuum. Ionization channels originating from occupied valence shell orbitals are considered, both in the separated- and interacting-channel approaches up to a photon energy of 100 eV. An accurate account of the effect of the interaction between the different excitation channels is found to be essential in order to reproduce the features observed in the experimental photoabsorption and photoionization spectra.