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 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 Hartree–Fock many-body perturbation theory for nuclear ground-states

2016 ◽  
Vol 756 ◽  
pp. 283-288 ◽  
Author(s):  
Alexander Tichai ◽  
Joachim Langhammer ◽  
Sven Binder ◽  
Robert Roth
Keyword(s):  
Perturbation Theory ◽  
Ground States ◽  
Many Body ◽  
Hartree Fock ◽  
Many Body Perturbation Theory

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

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>

scholarly journals Hartree-Fock and many body perturbation theory with correlated realisticNNinteractions

2006 ◽  
Vol 73 (4) ◽  
Author(s):  
R. Roth ◽  
P. Papakonstantinou ◽  
N. Paar ◽  
H. Hergert ◽  
T. Neff ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Many Body ◽  
Hartree Fock ◽  
Many Body Perturbation Theory

Dielectronic recombination and satellite line spectra of highly charged tungsten ions1This article is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas.

2011 ◽  
Vol 89 (5) ◽  
pp. 581-589 ◽  
Author(s):  
U.I. Safronova ◽  
A.S. Safronova ◽  
P. Beiersdorfer
Keyword(s):  
Perturbation Theory ◽  
Excited States ◽  
Transition Probabilities ◽  
Dielectronic Recombination ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Correct Identification ◽  
Many Body ◽  
International Colloquium ◽  
Many Body Perturbation Theory

We present our recent progress on theoretical studies that involve auto-ionizing states of highly charged tungsten ions. Such auto-ionizing states have two channels for decay, which requires that both radiative and auto-ionization atomic data be calculated and combined in a detailed study of the dielectronic recombination (DR). Three atomic codes are used to produce relativistic atomic data (energy levels, radiative transition probabilities, and auto-ionization rates). These are the relativistic many-body perturbation theory (RMBPT) code, the multiconfiguration relativistic Hebrew University Lawrence Livermore atomic code (HULLAC), and the Hartree–Fock relativistic (Cowan) code. Branching ratios relative to the first threshold and intensity factors are calculated for satellite lines, and DR rate coefficients are determined for the excited states. The total DR rate coefficient is derived as a function of electron temperature, and it is shown that the contribution of the highly excited states is very important for the calculation of the total DR rates. Synthetic dielectronic satellite spectra are constructed, and the atomic properties specific to the relevant tungsten ions are highlighted. First, we will consider the results for Na-like tungsten (W63+) and Mg-like tungsten (W62+) using all three codes. Then, we move to even higher ionization states and present the results in Li-like W (W71+). For this we use the RMBPT code as well as the quasi-relativistic many-body perturbation theory (MZ) code. The inclusion of the DR process is essential for correct identification of the lines in impurity spectra and for understanding the main contributions to the total radiation losses.

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