Alok K. S. Jha

Relativistic atomic data for W XLVII

Energy levels, radiative rates, and lifetimes are calculated for all levels of 3s23p, 3s23d, 3s3p2, 3s3d2, 3s3p3d, 3p23d, 3s3d2, 3p3d2, 3p3, and 3d3 configurations of Al-like tungsten ion (W XLVII). Multiconfigurational Dirac–Fock (MCDF) method is adopted for calculating energy levels and radiative rates. Oscillator strengths, radiative rates, and line strengths are reported for some E1 transitions from the ground level. Comparisons are made with the available data in the literature and good agreement has been found which confirms the reliability of our results.

Semi-relativistic calculations for the photoionization of neutral argon from its four lowest J-states

Semi-relativistic calculations are carried out for the photoionization of neutral argon from its ground state 3s23p61S0 and the lowest three excited levels 3s23p5(2P0)4s3P02, 3s23p5(2P0)4s 3P01 and 3s23p5(2P0)4s 3P00, using the semi-relativistic Breit–Pauli approximation. Configuration interaction (CI) wavefunctions are used to represent the lowest 12 target states of the Ar II ion retained in the R-matrix expansion. The Rydberg series 3s3p6 2S1/2{np[1/2]1, np[3/2]1}, J=1° of autoionizing resonances formed in the photoionization process of ground state 3s23p61S0, just below 3s3p6 2S1/2 threshold of Ar II, are identified and their resonance positions and effective quantum numbers are reported. Excellent agreement with previously published resonance positions and effective quantum numbers is observed. Further, new results for photoionization cross-sections from excited states of Ar, involving clusters of Feshbach resonances converging to different thresholds of Ar II, are predicted.

Lifetime for the Ti X spectrum

We present configuration interaction calculations for the lifetime of 294 fine-structure levels of the Ti X spectrum in the LSJ coupling scheme. The calculations include all the major correlation effects. The relativistic effects are included by adding the mass correction term, Darwin term and spin–orbit interaction term to the non-relativistic Hamiltonian in the Breit–Pauli approximation. The calculated lifetime values are in very close agreement with other available experimental and theoretical results. We have predicted new lifetime results for levels belonging to 3p23d, 3s24p, 3s3p4s, 3s3p4p and various other configurations of Ti X, where no other theoretical and experimental results are available.

Relativistic R-Matrix Close-Coupling Calculations for Photoionization of Si-Like Ni XV

We present relativistic close-coupling photoionization calculations of Al IV using the Breit-Pauli R-matrix method to obtain photoionization cross-section of Al IV from the ground state and the lowest two J=0 (even) excited states. A multi-configuration eigenfunctions expansion of the core Al V is employed with spectroscopic configurations 2s22p5, 2s2p6, 2s22p43s, 2s22p43p, 2s22p43d and 2s22p44s. We have included, for the first time, the lowest 68 level target states of Al V in the photoionization calculations of Al IV. Extensive configuration interaction wavefunctions are used to describe both the initial Al IV states and the final Al V states. Cross-sections are compared from three level calculations including only 2s2 2p5 2Po3/2, 1/2 and 2s 2p62S1/2 levels of Al V. The present calculation using the lowest 68 target levels of Al V are presented for the first time and should provide reasonably complete database for practical application for photoionization cross-section for Al IV, where high-energy cross-sections along with near-threshold photoionization cross-section is required.

Photoionization Cross Section for Ni XIX

The relativistic R-matrix method is used to calculate photoionization cross section for the ground state 1s22s22p6 1Se (J = 0) and the first four excited states (J = 0 even) of Ne-like Ni XIX, using the lowest 68 target states of Ni XX. Cross sections are dominated by Rydberg series of autoionizing resonances converging to several ionic states. We have compared our new 68-level cross sections with 32-level and with much lower 3-levels calculations. The 3-level results are found to be inadequate for practical applications due to the lack of complete set of resonances converging at higher thresholds. In our calculations, we have taken all the important physical effects like exchange, channel coupling, and short-range correlation, as well as relativistic effects into account. Our present results can be useful for modeling ionization balance of Ni XIX in laboratory and astrophysical plasmas. We believe that this is the first relativistic calculation for this ion to obtain the photoionization cross section.

Fine-structure energy levels, oscillator strengths and lifetimes of chlorine-like chromium

We have done relativistic calculations for the evaluation of energy levels, oscillator strengths, transition probabilities and lifetimes for Cr VIII ion. Use has been made of configuration interaction technique by including Briet-Pauli approximation. The energies of various levels from the ground state to excited levels of 3s3p6, 3s23p43d, 3s23p44s, 3s23p44d of Cr VIII are given in LSJ coupling scheme after fine-tuning and are compared with the experimental results compiled in the NIST Data Base. Many new lines have been predicted which have not appeared so far in the NIST Data.