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In this paper, we have described electron-correlation trends in the calculations of the hyperfine A and B constants for a few elements belonging to the Na isoelectronic sequence. The hyperfine A and B/Q values of the ground state 3s 2S 1/2 and the excited states 3p 2P 1/2, 3p 2P 1/2, 3d 2D 3/2, and 3d 2D 5/2 of the ions from Si 3+ to V 12+ are presented. The influence of the Breit interaction in the unretarded approximation to these hyperfine values is reported briefly. With increasing atomic number of this sequence, the variations of the different correlation contributing terms such as core correlations, core polarizations, and pair correlations are discussed in the framework of the relativistic coupled-cluster theory. The electron-correlation effect relative to the Dirac-Fock value in the hyperfine A constants of the 3d 2D 3/2,5/2 states follows unusual trends with increasing ionization. The relative pair-correlation effect influences the hyperfine constants of the fine-structure states of a term in an identical way at each species of this sequence. The presented relativistic coupled-cluster results are found to agree excellently with the other available results for a few ions. [ABSTRACT FROM AUTHOR]

In this paper, we study electron correlation and Gaunt interaction effects in ionization potentials (IPs) and hyperfine constants A of 2p2P1/2 and 2p2P3/2 states along with fine structure splitting (FSS) between them for the boron isoelectronic sequence using the relativistic coupled-cluster method. The range of atomic number z is taken from 8 to 21. The Gaunt contributions can be calculated at both the Dirac-Fock and the coupled-cluster levels from our presentation. Calculated IPs and FSS are compared with the results of the National Institute of Standards and Technology. Important correlation contributions like the core correlation, core polarization, and pair correlation effects are studied for hyperfine constants A. Many distinct features of the correlation and relativistic effects are observed in these studies. [ABSTRACT FROM AUTHOR]

In this paper, the El, £2, and Ml transition amplitudes are calculated along with the hyperfine A and B constants of doubly ionized gallium using the relativistic coupled-cluster approach. Electron correlations and the Gaunt interactions are considered to all orders using the coupled-cluster theory in a relativistic framework and their contributions are discussed explicitly in the calculations of all these amplitudes. Some interesting features of the correlation effects on the Gaunt interactions are noticed in the calculations of the hyperfine constants. The lifetimes of some low-lying states are also calculated using the transition amplitudes obtained by the present theory and the experimental transition energies. The calculated El transition amplitudes and lifetimes are in good agreement with the results obtained by the other theories and experiment. The hyperfine splitting of the ground states of In this paper, the El, £2, and Ml transition amplitudes are calculated along with the hyperfine A and B constants of doubly ionized gallium using the relativistic coupled-cluster approach. Electron correlations and the Gaunt interactions are considered to all orders using the coupled-cluster theory in a relativistic framework and their contributions are discussed explicitly in the calculations of all these amplitudes. Some interesting features of the correlation effects on the Gaunt interactions are noticed in the calculations of the hyperfine constants. The lifetimes of some low-lying states are also calculated using the transition amplitudes obtained by the present theory and the experimental transition energies. The calculated El transition amplitudes and lifetimes are in good agreement with the results obtained by the other theories and experiment. The hyperfine splitting of the ground states of 71Ga m and 69Ga III are found to be about 35 and 27.5 GHz, respectively, which shows the importance of these isotopes for the possible use of microwave frequency standards. The calculated hyperfine constants are associated with linewidth estimations of some transition lines in the visible and ultraviolet regions of electromagnetic spectrum. [ABSTRACT FROM AUTHOR]