CASCADE OF AUGER TRANSITIONS IN SPECTRUM OF XENON: THEORETICAL DATA

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.

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

Photoelectronics ◽

10.18524/0235-2435.2020.29.225622 ◽

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.

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

Photoelectronics ◽

10.18524/0235-2435.2020.29.225624 ◽

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.

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Many-Body Perturbation Theory Using the Density-Functional Concept: Beyond theGWApproximation

Physical Review Letters ◽

10.1103/physrevlett.94.186402 ◽

2005 ◽

Vol 94 (18) ◽

Cited By ~ 105

Author(s):

Fabien Bruneval ◽

Francesco Sottile ◽

Valerio Olevano ◽

Rodolfo Del Sole ◽

Lucia Reining

Keyword(s):

Perturbation Theory ◽

Density Functional ◽

Many Body ◽

Many Body Perturbation Theory ◽

Functional Concept

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Psi4 1.4: Open-Source Software for High-Throughput Quantum Chemistry

10.26434/chemrxiv.11930031.v1 ◽

2020 ◽

Author(s):

Daniel Smith ◽

Lori Burns ◽

Andrew Simmonett ◽

Robert Parrish ◽

Matthew Schieber ◽

...

Keyword(s):

Perturbation Theory ◽

Quantum Chemistry ◽

Open Source ◽

Density Functional ◽

Many Body ◽

Hartree Fock ◽

Large Numbers ◽

Many Body Perturbation Theory ◽

Infrastructure Project ◽

Job Specification

<div> <div> <div> <p>Psi4 is a free and open-source ab initio electronic structure program providing Hartree–Fock, density functional theory, many-body perturbation theory, configuration interaction, density cumulant theory, symmetry-adapted perturbation theory, and coupled-cluster theory. Most of the methods are quite efficient thanks to density fitting and multi-core parallelism. The program is a hybrid of C++ and Python, and calculations may be run with very simple text files or using the Python API, facilitating post-processing and complex workflows; method developers also have access to most of Psi4’s core functionality via Python. Job specification may be passed using The Molecular Sciences Software Institute (MolSSI) QCSchema data format, facilitating interoperability. A rewrite of our top-level computation driver, and concomitant adoption of the MolSSI QCArchive Infrastructure project, make the latest version of Psi4 well suited to distributed computation of large numbers of independent tasks. The project has fostered the development of independent software components that may be reused in other quantum chemistry programs. </p> </div> </div> </div>

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