U. I. Safronova

Comparison of calculated and measured wavelengths of resonance transitions in He-like ions for Z = 16-39

The specified calculation of wavelengths of resonance transitions in He-like ions (Z = 16-39) is compared with the results of the X-ray measurements in the spectra of low-inductance vacuum spark in the present paper. The calculation was made by Z-expansion method in the screening representation with the inclusion of relativistic and radiative effects. The experimental data have been obtained with compensation of the Doppler shift and taking into account the correction caused by the presence of adjoining satellites with n = 3. A slight difference between the theory and the experiment in the region Z = 38, 39 has been found.

Dielectronic recombination rate coefficients to the excited states of CIII from CIV

Abstract Energy levels, radiative transition probabilities and autoionization rates for CIII including 1s22pnl′ [n = 2–6, l′ ≤ (n − 1)] and 1s23lnl′ [n = 3–6, l′ ≤ (n − 1)] states were calculated by using the multi-configurational Hartree-Fock method (Cowan code). Autoionizing levels above the 1s22s and 1s22p thresholds were considered and their contributions were computed. Branching ratios on the autoionization rate to the first threshold and intensity factors were calculated for satellite lines of the CIII ion. The dielectronic recombination rate coefficients to the excited states for n = 2–6 were calculated. The values for the excited states higher than n = 6 were extrapolated and the total dielectronic recombination rate coefficients were derived. The rate coefficients to the excited states were fitted to an analytical formula and the fit parameters are given.

Autoionization states of lithium-like ions with large principal quantum number

Abstract The energy levels of the 1 s 2 lnl ( n = 3 and 4) configurations for ions with Z between 10 and 54 were calculated by using two theoretical methods: the perturbation theory method using Z -expansion (MZ) and the multiconfiguration Dirac-Fock method (MCDF). The asymptotic dependence of the energy matrix of the 1 s 2 lnl states on the principal quantum number n is discussed. Comparison between the two theoretical methods are given for the 1 s 2 l 3 l and 1 s 2 l 4 l configurations.

Energies and autoionization rates for Be-like systems. comparison of two methods: AUTOLSJ and MZ

Energy and autoionization rate for Be-like systems (1s2s22p, 1s2s2p2, 1s2p3) with Z = 6-42 have been calculated with two methods: AUTOLSJ (SUPERSTRUCTURE: including only the configurations of the complexes: 1s2s22p, 1s2p3 and 1s2s2p2) and (MZ) perturbation theory methods. Non-relativistic and relativistic parts of the energy have been considered separately. Relativistic effects have been taken into account by the Breit-Pauli operators. Non-relativistic and relativistic autoionization decay have been compared in the two methods, the contributions of 1s22s and 1s22p decay channels have been investigated.

Relativistic perturbation method for two-electron systems

The perturbation theory on the relativistic basis has been applied to calculate the energies of two-electron systems. The results for the energy of noninteracting electrons have been taken from the work by Johnson and Soff. For the first order both a precise calculation has been made and an αZ-expansion has been obtained. For the second order a precise calculation of the nonrelativistic limit is available, i.e. that of the first term of the αZ-expansion. Subsequent terms of the αZ-expansion have been evaluated on the basis of the screening constant method. General formulae for the first and second orders for any states of a two-electron system are given. Numerical results of the ionisation potential are given for the states 1s2½, 1s½ 2s½, 1s½ 2pj with Z = 10-100.

Z-dependences of the atomic characteristics for 1s2l2l′ states of three electron systems

Abstract Two different calculational methods (MZ and MCDF) are used to obtain energy levels, radiative rates, autoionization rates, satellite intensity factors, and fluorescence yields for doubly-excited states 1s2l2l′ of three electron systems. The energy levels and atomic characteristics obtained by the two methods are compared by ordering all the states by energy within each block of a given angular momentum J and parity. The Z dependences of the quantities are investigated for each calculational method for 10 ⩽Z ⩽ 54. The final comparison shows good agreement between the results obtained by the two methods.

Excitation collision strengths, cross-sections and rate coefficients for O V, Si XI, Fe XXIII and Mo XXXIX by electron impact (1s22s2- 1s22s2p- 1s22p2 transitions)

Excitation collision strengths, cross-sections and rate coefficients by electron impact are calculated for the transitions among 1s22s2, 1s22s2p, 1s22p2 levels of Be-like system of O V, Si XI, Fe XXIII and Mo XXXIX ions by Coulomb-Born approximation with exchange including relativistic effect and configuration interactions. The theoretical method for calculation is described and the results are compared with previous calculations. Numerical data and comparison are presented in tables as well as in figures. Two kinds of fitting formulae for cross-sections and rate coefficients are discussed.

Energy levels 1s22lnl' (n = 2, 3, 4) of Na VIII – S XIII ions. comparison of two calculation methods: MCDF and MZ

Energy levels of the 1s22l3l and 1s22l4l configurations for the ions with Z = 11-16 were calculated by using two calculation methods: many configuration Dirac-Fock (MCDF) and theory of perturbations by 1/Z. Contributions of correlation, relativistic and radiation effects and Z-dependence of these effects are discussed. The comparative analysis of calculated results and comparison of the results with available experimental data were carried out.

Z-dependences of the energy levels and autoionization rates for 2141′ states of two electron systems

Abstract Three different calculational methods (AUTOLSJ, MZ, MCDF) are used to obtain energy levels and autoionization rates for doubly-excited states 2141′ of two electron systems (10⩽ Z ⩽42). By ordering all the states by energy within each block of a given angular momentum J and parity, it becomes possible to compare energy levels and autoionization rates obtained by the three methods. The Z dependences of the quantities are investigated for each calculational method for 10⩽ Z ⩽42. The final comparison reveals rather good agreement between the results obtained by the three methods.

Model potential method for the calculation of the atomic characteristics of Ne-like systems

The calculation of the energy of Ne-like ions was carried out on the basis of the model potential method. Possibilities and advantages of the method are discussed. Calculated results were obtained for the states 1s22s2p63l with l = s, p, d. The comparison with another calculation and experiment is presented for the ions with Z = 30, 34, 36, 39, 47, 49, 54. Z-dependencies of the energy levels are discussed. Transition probabilities and oscillator strengths were calculated for all types of transitions (2-3, 2-2, 3-3). The comparison of this calculation with other theoretical calculations was carried out for the ions with Z = 30, 34, 36, 39. Questions about level transpositions are discussed. Results of asymptotic approximation and direct calculations are compared for line strengths of the transitions 2-2 and 3-3 (S) for the ion U82+.