Correlation and relativistic effects for 3l3l'autoionization states

Abstract

For autoionizing levels converging to the N = 3 threshold of He-like ions with Z = 3–26, energies and widths obtained within the generalized diagonalization approach are compared with the results of S-matrix perturbation theory. The combined data for the expansion coefficients can improve the validity of spectral calculations. Autoionization decay amplitudes and widths are obtained using both unscreened and screened hydrogenic orbitals for the free electron, as well as in the first order in continuum Coulomb coupling. Terms of order 1/Z can be extracted to improve the perturbational data for autoionization amplitudes, involving both screening corrections and the first-order continuum coupling. The relative significance of various atomic interactions in evaluating autoionization decay amplitudes is discussed.

Calculations of (nl)2and (3lnl′) autoionizing states in two-electron systems

“…Here, the agreements between the calculations are seen to be good. It should be underlined again that the present results for 2p 2 level are close to the values of Ho and Bhatia [16] for Z = 2-4 and to those of Ivanov and Safronova [12] for Z = 5-8. In addition, for the 4p 2 level, comparison indicates that our results match better with the complex rotation calculations [16] up to Z = 10.…”

“…This lack of accuracy is due to the fact that previously [2], the dependence of the β parameter on the principal quantum number has been neglected. Table 3 shows a comparison of our results for nd 2 1 G states with those obtained by Bachau et al [17], Biaye et al [11], Ivanov and Safronova [12] and with those obtained by Ho [18]. For 3d 2 , 4d 2 and 5d 2 states, the agreements between the calculations are seen to be very satisfactory.…”

“…It should be mentioned that our results for 2s 2 , 3s 2 and 4s 2 match more with the complex rotation calculations [10,13,14] up to Z = 10. In table 2, we present our calculations for np 2 1 D states and compare the results obtained to previous calculations [2] and to the data of Ho and Bhatia [16], Biaye et al [11], Ivanov and Safronova [12] and Roy et al [15]. Here, the agreements between the calculations are seen to be good.…”

“…The results obtained in the present work using equation ( 5) for ns 2 1 S, np 2 1 D, nd 2 1 G and nf 2 1 I with n 5 in the helium-like ions up to Z = 10 are listed in tables 1-3 and compared to various other calculations [2,[10][11][12][13][14][15][16][17][18]. Table 1 shows a comparison of the present calculations for ns 2 1 S states with the complex rotation results of Ho [10,13,14], the variational Hylleraas-type results of Biaye et al [11], the double sums over the complete hydrogen spectrum values of Ivanov and Safronova [12], the density functional theory (DFT) of Roy et al [15] and with previous work [2]. Here, the agreements between the calculations are generally good.…”

Resonance yields and excitation cross sections for atomic ionization

“…It is definitely valid for Feshbach resonances. Thus, it has been shown that ( 12) holds for resonant photoionization in the most complex cases, when there are many interfering autoionization states decaying into strongly coupled ionization channels, including relativistic corrections through the Breit operator, as well as allowing for the interference of radiative and radiationless mechanisms of decay (Ivanov 1989, Ivanov andSafronova 1994 andreferences therein). It remains valid for ionization of atoms and ions by charged particles in a broad region of energies, including the processes of the restructurization of the system projectile plus target into an essentially three-particle system in the course of the collision (kinematic recoupling, one of the possible manifestations of post-collision interactions (Godunov et al 1989)).…”