scholarly journals RELATIVISTIC CALCULATION OF WAVELENGTHS AND E1 OSCILLATOR STRENGTHS IN Li-LIKE MULTICHARGED IONS AND GAUGE INVARIANCE PRINCIPLE

2021 ◽  
pp. 134-142
Author(s):  
O. Khetselius ◽  
A. Mykhailov
Keyword(s):  
Perturbation Theory ◽  
Invariance Principle ◽  
Gauge Invariance ◽  
Oscillator Strengths ◽  
Relativistic Energy ◽  
Many Body ◽  
Zeroth Order ◽  
Many Body Perturbation Theory ◽  
Precise Experiment ◽  
Particle Approximation

The spectral wavelengths and oscillator strengths for 1s22s (2S1/2) → 1s23p (2P1/2) transitions in the Li-like multicharged ions with the nuclear charge Z=28,30 are calculated on the basis of the combined relativistic energy approach and relativistic many-body perturbation theory with the zeroth order optimized Dirac-Kohn-Sham one-particle approximation  and gauge invariance principle performance. The comparison of the obtained results with available theoretical and experimental (compilated) data is performed. The important point is linked with an accurate accounting for the complex exchange-correlation (polarization) effect contributions and using the optimized one-quasiparticle representation in the relativistic many-body perturbation theory zeroth order that significantly provides a physically reasonable agreement between theory and precise experiment.

scholarly journals CASCADE OF AUGER TRANSITIONS IN SPECTRUM OF XENON: THEORETICAL DATA

2021 ◽  
pp. 94-101
Author(s):  
A. Chernyshev ◽  
E. Efimova ◽  
V. Buyadzhi ◽  
I. Nikola
Keyword(s):  
Perturbation Theory ◽  
Density Functional ◽  
Atomic System ◽  
Theoretical Data ◽  
Semiempirical Method ◽  
Relativistic Energy ◽  
Many Body ◽  
Zeroth Order ◽  
Exchange Correlation ◽  
Many Body Perturbation Theory

The energy parameters of the Auger transitions for the xenon atomic system are calculated within the combined relativistic energy approach and relativistic many-body perturbation theory with the zeroth order density functional approximation. The results are compared with reported experimental data as well as with those obtained by semiempirical method. The important point is linked with an accurate accounting for the complex exchange-correlation (polarization) effect contributions and using the optimized one-quasiparticle representation in the relativistic many-body perturbation theory zeroth order that significantly provides a physically reasonable agreement between theory and experiment.

scholarly journals THEORETICAL STUDYING EXCITED STATES SPECTRUM OF THE YTTERBIUM WITHIN THE OPTIMIZED RELATIVISTIC MANY-BODY PERTURBATION THEORY

2021 ◽  
pp. 118-125
Author(s):  
V. Ternovsky ◽  
A. Svinarenko ◽  
Yu. Dubrovskaya
Keyword(s):  
Perturbation Theory ◽  
Excited States ◽  
Theoretical Data ◽  
Zeroth Approximation ◽  
Relativistic Energy ◽  
Many Body ◽  
Hartree Fock ◽  
Ytterbium Atom ◽  
Many Body Perturbation Theory ◽  
Experimental Values

Theoretical studying spectrum of the excited states for the ytterbium atom is carried out within the relativistic many-body perturbation theory with ab initio zeroth approximation and generalized relativistic energy approach.  The zeroth approximation of the relativistic perturbation theory is provided by the optimized Dirac-Kohn-Sham ones. Optimization has been fulfilled by means of introduction of the parameter to the Kohn-Sham exchange potentials and further minimization of the gauge-non-invariant contributions into radiation width of atomic levels with using relativistic orbital set, generated by the corresponding zeroth approximation Hamiltonian. The obtained theoretical data on energies E and widths W of the ytterbium excited states are compared with alternative theoretical results (the Dirac-Fock, relativistic Hartree-Fock, perturbation  theories) and available experimental data. Analysis shows that the theoretical and experimental values ​​of energies are in good agreement with each other, however, the values ​​of widths differ significantly. In our opinion, this fact is explained by insufficiently accurate estimates of the radial integrals, the use of unoptimized bases, and some other approximations of the calculation.

scholarly journals RELATIVISTIC ENERGY APPROACH AND MANY-BODY PERTURBATION THEORY TO COMPUTING ELECTRON-COLLISION CROSS-SECTIONS OF COMPLEX MULTIELECTRON IONS

2021 ◽  
pp. 102-109
Author(s):  
V. Buyadzhi
Keyword(s):  
Perturbation Theory ◽  
Cross Sections ◽  
Matrix Method ◽  
Energy Approach ◽  
Electron Collision ◽  
Relativistic Energy ◽  
Many Body ◽  
R Matrix ◽  
Collision Cross Sections ◽  
Many Body Perturbation Theory

An advanced relativistic energy approach combined with a relativistic many-body perturbation theory with ab initio zeroth approximation  is used to calculate the electron-collision excitation cross-sections for complex multielectron systems.  The relativistic many-body perturbation theory is used alongside the gauge-invariant scheme to generate an optimal Dirac-Kohn-Sham- Debye-Hückel one-electron representation.  The results of relativistic calculation (taking into account the exchange and correlation corrections) of the electron collision cross-sections of excitation for the neon-like ion of the krypton  are presented and compared with alternative results calculation on the basis of the R-matrix method in the Breit-Pauli approximation, in the relativistic distorted wave approximation and R- matrix method in combination with Dirac-Fock approximation

scholarly journals NEW RELATIVISTIC APPROACH TO COMPUTING SPECTRAL PARAMETERS OF MULTICHARGED IONS IN PLASMAS

2021 ◽  
pp. 60-67
Author(s):  
E. Ternovsky ◽  
A. Mykhailov
Keyword(s):  
Perturbation Theory ◽  
Electron Density ◽  
Nuclear Interaction ◽  
Exchange Potential ◽  
Relativistic Energy ◽  
Many Body ◽  
Spectral Parameters ◽  
Debye Shielding ◽  
Relativistic Approach ◽  
Many Body Perturbation Theory

It is presented  a new relativistic approach to computing the spectral parameters of multicharged ions in plasmas for different values of the plasmas screening (Debye) parameter (respectively, electron density, temperature). The approach used is based on the generalized relativistic energy approach combined with the optimized relativistic many-body perturbation theory (RMBPT) with the Dirac-Debye shielding model as zeroth approximation, adapted for application to study the spectral parameters of ions in plasmas. An electronic Hamiltonian for N-electron ion in plasmas is added by the Yukawa-type electron-electron and nuclear interaction potential. The special exchange potential as well as the electron density with dependence upon the temperature are used.

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