Calculation of excitation and ionization processes using relativistic CCC method

The recently formulated relativistic convergent close-coupling (RCCC) method has been applied to electron scattering from quasi-one electron atoms [1] and also highly charged hydrogenlike ions [2]. In the latter case it has been used to resolve discrepancies between theory and experiment for the polarization of x-rays emitted by hydrogenlike ions (Ti$^{21+}$, Ar$^{17+}$, Fe$^{25+}$) during electron impact excitation and make predictions for cross sections and radiation polarization for hydrogen-like uranium ion. Here we report on the extension of the RCCC method to accommodate electron scattering from two electron targets and quasi-two electron targets. We apply the theory to electron scattering from mercury which serves as a testing ground for relativistic theories due to its high atomic number, $Z=80$. Furthermore, electron-mercury scattering plays an important practical role in the physics of fluorescent and high intensity discharge lamps. In our calculations the mercury atom was modeled as a quasi-two electron atom consisting of two valence electrons above an inert $[Xe]4f^{14}5d^{10}$ frozen core. One- and two-electron polarization potentials have been used to model more accurately the valence-core-electrons correlations. We have calculated cross sections for electron impact excitations of mercury for a large number of transitions. Good agreement was found with our previous nonrelativistic results for the transitions that are not strongly affected by relativistic effects (e.g., $(6s6p){}^1P^o_{1}$). For the transitions that are strongly affected by relativistic effects (e.g., $(6s6p){}^3P^o_{1}$) we find good agreement with recent DBSR calculations [3] and available experiment.\\[4pt] [1] D. V. Fursa and I. Bray, Phys. Rev. Lett. {\bf 100}, 113201 (2008).\\[0pt] [2] C. J. Bostock, D. V. Fursa, and I. Bray, Phys. Rev. A {\bf 80}, 052708 (2009).\\[0pt] [3] O. Zatsarinny and K. Bartschat, Phys. Rev. A {\bf 79}, 042713 (2009).