OK-shell photoemission of the CO molecule: comparison between theory and experiment

Photoionization cross sections, dipole matrix elements and phase shifts are calculated for the O K-shell of the CO molecule using two theoretical models. One of them is a new version of the relaxed core Hartree-Fock approximation with a fractional charge. The value of this charge is considered as a fitting parameter. In this paper, the fractional charge 0.7 was used which gives a correct position of the maximum of the sigma* shape resonance in the photoionization cross section. The other model is a modification of the multiple scattering method with overlapping atomic spheres. The dipole matrix elements and phase shift differences calculated by these two methods are compared with the corresponding values determined from the complete experiment by Cherepkov et al (2000 J. Phys. B: At. Mol. Opt. Phys. 33 4213).