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The energies and the widths of the Stark resonances for the hydrogen atom are calculated using a new approach. It is based on the operator form of the perturbation theory of the Schrodinger equation. The method includes the physically reasonable distorted-waves approximation in the frame of the formally exact quantum-mechanical procedure. The zero-order Hamiltonian possessing only stationary states is determined only by its spectrum without specifying its explicit form. The method of calculation of the perturbation theory matrix elements is described.

used during the construction of the model potential (MP) and one-quasi-particle wave functions of the zeroth approximation, for the calculation of one-quasi-particle diagram contributions, and also for the effective Calculation Of some second order two-The relativistic perturbation theory is applied to the solution of the manyelectron Dirac equation. The theoretical consideration is accomplished for Some Mg-like ions: s v, Ca IX, ~i XI and F~ xv; the energies of all the states l?2s22p631, j l , 3 1 j 2 are calculated. The Ne-like spectra are calculated for the ions with Z = 16-26; all the states of configurations ls22s22ps3s, 3p, 3d and ls22s2p63s, 3p, 3d are considered.The Dirac equation with the central one-particle model potential VJr) is accepted as a zeroth approximation; the model potential imitates the core potential of the closed shells. The empirical information about the energy structures of one electron above the core or one vacancy inside the core is used here to construct the zeroth approximation.The perturbation theory first order correction is calculated exactly, the high order contributions are accounted for effectively. Two main types of high order corrections are investigated: "polarization" interaction of two "above core" particles and effect of the mutual screening of these particles.quasi-particle diagram contributions. Calculations previously made for the ions of the Mg-like series and the Fe-l&e series (two vacancies above the core 3p63d1') showed that already an elementary calculation within the first order of the PT yields cated multi-configurational Hartree-Fock-Pauli method.In the present paper a regular method for the effective inclusion of high order corrections is described. F~~ ions of the Mg I-like and Ne I-like series the allowance for these corrections appreciably improves the results for the transition energies.Of the Same quality as the more sophisti-

ABSTRACT:We present the uniform energy approach, formally based on the quantum electrodynamics, using the gauge invariant scheme of generation of the optimal one-electron representation, for the calculation of electron-collision strengths and cross sections. The aim is to study, in a uniform manner, elementary processes responsible for emission-line formation in plasmas. The electron-collision excitation cross sections and strengths for some Ne-like ions (Fe, Ba) are calculated. To test the results of calculations, we compare them with the calculations of other investigators and with the available experimental data.

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