Photoionization Cross Sections and Asymmetry Parameters for Ethylene

A Multichannel Least-Squares B-Spline Approach to Molecular Photoionization: Theory, Implementation, and Applications within the Configuration–Interaction Singles Approximation

“…In fact, both frozen-core HF (FCHF) and continuum multiple scattering (CMS) calculations are not able to predict the strong oscillatory behavior of the experimental data in this energy range but show a smooth decreasing behavior. 61,66 In the near-threshold energy range, the CIS-5ch profile is in somewhat better agreement with both TDDFT and the experimental data, compared to the CIS-2ch profile. However, there are some discrepancies between ionization of H 2 .The available experimental data from the literature 78,79 have also been reported.…”

“…It is interesting to note (i) the good agreement between TDDFT and CIS-5ch profiles for both partial cross section and asymmetry parameter and (ii) the CIS-2ch calculation gives results in better agreement with the experimental data, which is surprising, and probably fortuitous, but consistent with the good agreement between the experimental data and predictions from single-channel theories, as observed in the literature. 61,66 For higher excitation energies, the calculated cross-sectional profiles rapidly converge to the experimental data available, while the CIS-5ch and TDDFT asymmetry parameter profiles are observed to underestimate the experimental data.…”

“…Earlier CMS and FCHF calculations predicted, in agreement with our CIS-2ch results (not shown in the figure), the occurrence of shape resonances in the kb 1u and kb 2u channels, and are in surprisingly good agreement with the available experimental data for both cross section and asymmetry parameter profiles. 61,66 In addition to this resonant behavior, both CIS-5ch and TDDFT calculations predict the occurrence of autoionizating decay of excited states, giving rise to strong modulations that have been partially washed out by the convolution procedure. It is interesting to note (i) the good agreement between TDDFT and CIS-5ch profiles for both partial cross section and asymmetry parameter and (ii) the CIS-2ch calculation gives results in better agreement with the experimental data, which is surprising, and probably fortuitous, but consistent with the good agreement between the experimental data and predictions from single-channel theories, as observed in the literature.…”

“…Above a photon energy of 20 eV, the agreement between theoretical profiles (CIS-5ch, TDDFT) and the experiment can be considered quantitative, at variance with earlier FCHF and CMS results. 61,66 The near-threshold dynamics of the 1b 3g −1 ionization carries signatures of both one-electron and multielectron resonances. Earlier CMS and FCHF calculations predicted, in agreement with our CIS-2ch results (not shown in the figure), the occurrence of shape resonances in the kb 1u and kb 2u channels, and are in surprisingly good agreement with the available experimental data for both cross section and asymmetry parameter profiles.…”

Photoionization cross sections and asymmetry parameters for silane

“…This procedure has proven to be numerically robust and capable of providing a quantitative description of the photoionization dynamics in molecular systems studied to date. [23][24][25][26] Although this method was developed in the early eighties for photoionization studies of linear systems, 23,24 it has been extended to nonlinear polyatomic molecules 25,26 and still constitutes one of a few tools for carrying out ab initio calculations of cross sections and asymmetry parameters for photoionization of such systems. The comparison between the calculated results, even in the exact static-exchange ͑SE͒ level, with the experimental data would provide information on the role played by important physical effects, e.g., target electronic correlation, multichannel coupling, correlation-polarization effects, etc., not included in the calculations.…”