Relativistic structure description and relaxation effect on krypton 4p(5)(P-2(3/2,1/2))5s excitation at small squared momentum transfer

Relativistic generalized oscillator strengths (GOSs) at small squared momentum transfer (K-2 less than or equal to 1 all) for krypton 4p(5)(P-2(1/2,3/2))5s excitations are studied in detail under the first-order Born approximation based on the Dirac-Fock (DF) and Dirac-Fock-Slater (DS) theories. Comparisons are made with the existing experiment at 300 and 500 eV. The large GOS difference between the local-type and non-local-type exchange interactions in the target, and the large influence of the relativistic effects on the GOS are shown at K-2 less than 0.1. Particularly, the relaxation effect between the ground- and excited-state single configurations, and the Coulomb correlation effect by a model potential as a function of local density are investigated. Comparisons with the experiment show that the relaxation effect is more important than the correlation effect. The present DF calculation, although not involving the non-local correlation, yields both the GOS and the excitation energy closer to the experimental values than the DS calculation, due to the very small correlation effect in the outer-shell excitations. Results of krypton show that the average-configuration-state approximation in the DF theory is suitable to describe the excited-state single configuration including 4p(1)4p(4)5s(1) and 4p(2)4p(3)5s(1) subshells.