Relativistic convergent close-coupling method: Calculation of electron scattering from hydrogenlike ions

We report on the extension of the recently formulated relativistic convergent close-coupling (RCCC) method to include the Breit and Møller interactions. The inclusion of these relativistic effects ensures that the RCCC method is now capable of calculating electron scattering excitation and ionization cross sections for highly charged ions. We have calculated the polarization of the Lyman-α₁ x-ray line emitted by hydrogenlike Ti²¹⁺, Ar¹⁷⁺, and Fe²⁵⁺ ions excited by electron impact. We find that account of Breit relativistic corrections is important to resolve the discrepancy between experiment and theoretical calculations. For the much heavier hydrogenlike U⁹¹⁺ ion where the Møller interaction becomes important we present the estimate of the polarization of the Lyman-α₁ x-ray line and performed a calculation of the total ionization cross section.