Level energies, wavelengths, electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition rates, oscillator strengths, and line strengths from combined relativistic configuration interaction and many-body perturbation calculations are reported for the 201 fine-structure states of the 2s 2 2p 6 , 2s 2 2p 5 3l, 2s2p 6 3l, 2s 2 2p 5 4l, 2s2p 6 4l, 2s 2 2p 5 5l, and 2s 2 2p 5 6l configurations in all Ne-like ions between Cr XV and Kr XXVII. Calculated level energies and transition data are compared with experiments from the NIST and CHIANTI databases, and other recent benchmark calculations. The mean energy difference with the NIST experiments is only 0.05%. The present calculations significantly increase the amount of accurate spectroscopic data for the n > 3 states in a number of Ne-like ions of astrophysics interest. A complete dataset should be helpful in analyzing new observations from the solar and other astrophysical sources, and is also likely to be useful for modeling and diagnosing a variety of plasmas including astronomical and fusion plasma.

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Wavelengths and oscillator strengths for transitions among the levels of the terms belonging to the 3s2, 3s3p, 3s3d, 3s4s, 3s4p, 3s4d, 3p2, 3p3d, 3p4s, 3p4p, 3p4d, 3d4s, 3d4p, 3d4d and 3d2 configurations of Mg-like Nd48+, Pm49+ and Sm50+ are systematically calculated using multiconfiguration-Dirac–Fock method. The predicted spectra of these three ions are, for the first time, extensively reported for n = 3–4 transitions in the 5–8 Å range and the variant trends of wavelengths and oscillator strengths along the isoelectronic sequence are discussed.

The multiconfiguration Dirac–Fock method is used to systematically calculate the energy levels, wavelengths and oscillator strengths for transitions among the levels of the terms belonging to the 3s2, 3s3p, 3s3d, 3s4s, 3s4p, 3s4d, 3p2, 3p3d, 3p4s, 3p4p, 3p4d, 3d4s, 3d4p, 3d4d and 3d2 configurations for the elements of the magnesium isoelectronic sequence from high nuclear charge Z = 53 to 58 by taking into account main correlation relativistic effects. Another wavelength region λ = 6–11 Å from n = 3–4 transitions and the corresponding oscillator strengths are for the first time extensively reported. The trends of wavelengths and oscillator strengths along the isoelectronic sequence are discussed. Many strong configuration mixings and level-crossings in particular between the two states 3p3d 3F30 and 3p3d 3D30 in Mg-like La and Ce ions are investigated.

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