scholarly journals Atomic Structure Calculations for Neutral Oxygen

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Norah Alonizan ◽  
Rabia Qindeel ◽  
Nabil Ben Nessib

Energy levels and oscillator strengths for neutral oxygen have been calculated using the Cowan (CW), SUPERSTRUCTURE (SS), and AUTOSTRUCTURE (AS) atomic structure codes. The results obtained with these atomic codes have been compared with MCHF calculations and experimental values from the National Institute of Standards and Technology (NIST) database.

2017 ◽  
Vol 95 (10) ◽  
pp. 950-957
Author(s):  
Arun Goyal ◽  
Rinku Sharma ◽  
A.K. Singh ◽  
Man Mohan

We report accurate calculations of W XLIV through application of multi-configuration Dirac–Fock wave functions. We have calculated the energies for the lowest 100 fine structure levels, transition wavelengths, radiative rates, oscillator strengths, and line strengths for electric (E1) and magnetic dipole (M1) transitions with the extended average level multi-configurational Dirac–Fock method in the General-Purpose Relativistic Atomic Structure Package (GRASP). We have taken into account the electron correlations, quantum electrodynamics (QED) and Breit corrections in our calculations. We have also performed parallel calculations with the flexible atomic code (FAC) to assess the accuracy of our calculations. This is a fully relativistic code that provides a variety of atomic parameters, and (generally) yields results for energy levels and radiative rates comparable to GRASP. Our calculated results match well with experimentally observed results that are obtained in ASDEX upgrade Tokamak. Additionally, we have also provided the line intensity ratios and electron density for W XLIV, which is useful and important in plasma diagnostics and modeling in future International Thermonuclear Experimental Reactor (ITER) experiments. We believe that our results would be beneficial in the areas of fusion plasma research and astrophysical investigations and applications.


2014 ◽  
Vol 92 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Man Mohan ◽  
Sunny Aggarwal ◽  
Narendra Singh

Energy levels, lifetimes, and wavefunction compositions have been calculated for all levels of odd parity 3s23p5 ground configuration as well as 3s3p6 and 3s23p43d even parity excited configurations in highly charged Cl-like tungsten ion. Transition probabilities, oscillator strengths, and line strengths for E1, E2, M1, and M2 transitions have been obtained using the fully relativistic multiconfiguration Dirac–Fock (MCDF) approach including the correlations within the n = 3 complex, some n = 3 → n = 4 single and double excitations and Breit and quantum electrodynamics effects. For comparison from our calculated energy levels, we have also calculated the energy levels by using the fully relativistic flexible atomic code (FAC). The validity of the method is assessed by comparison with previously published experimental and theoretical data. The excellent agreement observed between our calculated results and those obtained using different approaches confirm the accuracy of our results. Additionally, we have predicted some new atomic data for W57+ that are not available so far and may be important for plasma diagnostic analysis in fusion plasma.


2015 ◽  
Vol 93 (5) ◽  
pp. 487-495 ◽  
Author(s):  
Arun Goyal ◽  
Indu Khatri ◽  
Sunny Aggarwal ◽  
A.K. Singh ◽  
Man Mohan

Energy levels, wavefunction compositions, and lifetimes are computed for all levels of 4s24p5, 4s24p44d, and 4s4p6 configurations in Br-like ions (Z = 47–50). We use the multiconfigurational Dirac–Fock method to generate the wavefunctions. We also present the transition wavelengths, oscillator strengths, transition probabilities, and line strengths for the electric dipole (E1) transition from the ground state configuration. We compare our calculated results with the available data in the literature and good agreement is obtained, which confirms the quality of our results. Moreover, we predict some new atomic data that have not been available so far and may be important for plasma diagnostic analysis in fusion plasma.


2014 ◽  
Vol 92 (11) ◽  
pp. 1285-1296 ◽  
Author(s):  
Sunny Aggarwal ◽  
Nupur Verma ◽  
A.K. Singh ◽  
Narendra Singh ◽  
Rinku Sharma ◽  
...  

We present accurate atomic structure calculations for the lowest 200 fine structural energy levels for oxygen-like nickel, which may be a useful ion for both astrophysical and fusion plasmas. For the calculations of energy levels and radiative rates, we have used the multiconfigurational Dirac–Fock method. Our results are compared with those obtained using other numerical methods and experiments so that their accuracy can be assessed. The transition wavelengths, oscillator strengths, and radiative rates are reported for electric dipole (E1) transitions from the ground state. We have also presented the transition probabilities and transition wavelength of some forbidden transitions. Finally, we predict new energy levels, oscillator strengths, and transition probability data, where no other theoretical or experimental results are available, which may be useful for future experimental work.


2020 ◽  
Vol 75 (8) ◽  
pp. 739-747
Author(s):  
Feng Hu ◽  
Yan Sun ◽  
Maofei Mei

AbstractComplete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors and E1, E2, M1, and M2 line strengths, oscillator strengths, transitions rates are reported for the low-lying 41 levels of Mo XXVIII, belonging to the n = 3 states (1s22s22p6)3s23p3, 3s3p4, and 3s23p23d. High-accuracy calculations have been performed as benchmarks in the request for accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects in multi-valence-electron systems. Comparisons are made between the present two data sets, as well as with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in a good agreement with other theoretical and experimental values. The present results are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing plasmas.


Atoms ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 50
Author(s):  
Charlotte Froese Fischer

The paper reviews the history of B-spline methods for atomic structure calculations for bound states. It highlights various aspects of the variational method, particularly with regard to the orthogonality requirements, the iterative self-consistent method, the eigenvalue problem, and the related sphf, dbsr-hf, and spmchf programs. B-splines facilitate the mapping of solutions from one grid to another. The following paper describes a two-stage approach where the goal of the first stage is to determine parameters of the problem, such as the range and approximate values of the orbitals, after which the level of accuracy is raised. Once convergence has been achieved the Virial Theorem, which is evaluated as a check for accuracy. For exact solutions, the V/T ratio for a non-relativistic calculation is −2.


Atoms ◽  
2016 ◽  
Vol 4 (3) ◽  
pp. 22 ◽  
Author(s):  
Arun Goyal ◽  
Indu Khatri ◽  
Avnindra Singh ◽  
Man Mohan ◽  
Rinku Sharma ◽  
...  

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