Photoionization of mercury: A relativistic time-dependent density-functional-theory approach

The relativistic time-dependent density functional theory (RTDDFT) has been applied to the photoionization of mercury in the energy range from the threshold up to 300 eV, thus covering almost all the photon energy range for which experimental data are available. Partial cross sections and asymmetry parameter profiles for the 6s, 5d, 5p, and 4f subshells have been calculated and compared with earlier relativistic random-phase approximation and RTDDFT theoretical calculations and with the experimental results. A study of the spin polarization of photoelectrons from the outer subshells 6s and 5d at RTDDFT level is also presented. The use of the LB94 exchange-correlation potential together with an implementation of the RTDDFT equations in a B-spline basis set based on a noniterative procedure for the calculation of the induced response potential has permitted the study, at RTDDFT level, of the autoionization resonances converging to the 5d_3/2,5/2 and 5p_1/2,3/2 thresholds. Comparison of the RTDDFT results with the other theoretical and experimental data available confirms the effectiveness of the method in the description of correlation and relativistic effects in the photoionization of such a heavy system.