Z-scaledK-shell dielectronic recombination rate coefficients

Abstract

State-specific dielectronic recombination (DR) rate coefficients from ground states of H- and He-like Al, Ti, Ni, Kr, and Mo ions have been calculated in the isolated resonance and intermediate coupling approximation. The data generated for these calculations consists of energies of singly and doubly excited states, radiative rates, autoionization rates, and dielectronic recombination branching ratios. A Hartree-Fock method that includes relativistic corrections was employed in order to carry out the calculations. Three parameter fits to the data were then made using the Al, Ti, and Kr data to obtain scaling relations that enable one to calculate similar data for other ions by interpolation in the range between Al and Kr and somewhat beyond by extrapolation. The scaling accuracy was verified by comparing the scaling relation predictions to detailed data obtained for Ni and Mo calculations. The results obtained also compared well with other published work in which total ground state to ground state dielectronic recombination rates were calculated. The DR rate coefficients that are calculated from the scaled DR data are generally most accurate for intermediate to high-temperature collisional plasmas. However, in low-temperature photoionized plasmas, significant DR contributions come from the $\ensuremath{\Delta}n=0$ core excitations that are not present for K-shell recombination and thus one should expect the Z scaled DR rates to be accurate for any range of temperatures of interest.