Fully relativistic distorted-wave calculations for electron impact excitation of highly charged Nickel-like ions

A fully relativistic distorted-wave method and the corresponding procedure REIE06 have been developed recently to study the electron impact excitation processes of highly charged ions. In this study,we calculated the collision strengths, cross sections and rate coefficients for electron impact excitation of highly charged Nickel-like Gd36+, Rn58+-U64+ (Z = 86-92) ions from the ground state to 106 low-lying excitated states. In the calculations, the relativistic effects, electron correlation effects, Breit interactions and high partial wave contributions are considered systematically. Based on the calculations, we studied the contribution of Breit interaction to collision strengths, the cross sections connected with the strongest 4d-4p (J = 0-1) X-ray laser transitions along the Ni-like sequence,and the effects of strong configuration interaction on cross sections from the ground state 3d(101)S(0) to the (3d(3/2)4d(5/2))(1), (3d(3/2)4d(3/2))(1) and (3p(3/2)4p(1/2))(1) states. A comparison was made between the present results and previous theoretical calculations for collision strengths of Gd36+ and U64+ ions, and rate coefficients of Gd36+ ion, good agreement was obtained.