Breit–Pauli atomic structure calculations for sulphur-like titanium

Abstract

Configuration interaction calculation has been performed for excitation energies, oscillator strengths, and transition probabilities of 114 fine-structure levels of sulphur-like titanium. The relativistic effects are included in Breit–Pauli approximation by adding mass-correction, Darwin, and spin–orbit interaction terms to the nonrelativistic Hamiltonian. We have adjusted the diagonal elements of Hamiltonian matrices (fine-tuning) before the calculation of oscillator strength and transition probabilities for the electric dipole allowed transitions. Our calculated data are in close agreement with data listed in National Institute of Standards and Technology and other available results. Correct identification of some of the levels become very difficult because of strong mixing among several fine-structure levels. We predict new energy levels, oscillator strength, and transition probability data, where no other theoretical or experimental results are available, which will form the basis for future experimental work.

Energy levels and radiative rates for transitions in Ti VII

“…Differences in energy levels between our calculated results and the NIST listings (with revised term labels as listed here) are up to 0.1 Ryd for some of the higher levels. The energies reported by Bièmont [16] and Singh et al [15] are closer to the NIST values, because both have made adjustments whereas our calculations are ab initio. However, energies from the MCHF calculations by Froese-Fischer et al [17] are also closer to the NIST listings, although many levels are missing from the latter.…”

“…Many transitions are unfortunately missing from the CIV3 calculations of Singh et al [15] and some of these are comparatively strong, such as: 1-41, 2-41/45 and 3-41. Furthermore, discrepancies between the CIV3 f-values and other calculations listed in Table 6 are up to five orders of magnitude -see for example, transitions 1-16/31/33, 2-15/31/33/34, 3-17/31 and 4-36.…”

“…However, the contribution of the Breit and QED effects is negligible. Also included in this table are the experimental energies compiled by NIST [14] and the theoretical values obtained by Bièmont [16], Froese-Fischer et al [17] and Singh et al [15] from the HFR, MCHF and CIV3 codes, respectively.…”

“…There are no major discrepancies with our calculations, although the term labels of the levels differ in a few instances as noted in section 2.1. However, extensive comparisons have been possible, for about half of the levels, with other available theoretical work, particularly of Singh et al [15], as shown in Tables 1-3. Based on these comparisons it is concluded that CI is very important for the energy levels of Ti VII, but mostly among those configurations whose levels interact closely.…”

“…Available experimental data for energy levels have been compiled by the NIST (National Institute of Standards and Technology) team [13], [14]. Considering the importance of Ti ions, several calculations have been performed for Ti VII -see for example Singh et al [15] and references therein. However, two important ones are by Bièmont [16] and Froese-Fischer et al [17].…”