The spin-allowed and spin-forbidden - , transitions in the magnesium isoelectronic sequence

Abstract

Relativistic multiconfiguration Dirac - Fock (MCDF) transition energies and oscillator strengths are determined in an `optimal level' scheme for both the spin-allowed - and spin-forbidden 3 - transitions in the magnesium isoelectronic sequence through . The modest relativistic configuration mixing to represent the intravalence correlation is combined in MCDF calculations with a polarization model to account for valence - core electron correlation. For the first few members of the sequence (Mg I to Cl VI) rather extensive relativistic configuration interaction Dirac - Fock (CIDF) calculations (with and without core polarization) are also performed to improve the representation of the intravalence electron correlation which is important for the neutral end of the sequence. The influence of the intravalence correlation, as well as the valence - core electron correlation on oscillator strengths, excitation energies and ionization energies is investigated. The proper representation of the intravalence electron correlation is found to be crucial for oscillator strength calculations near the neutral end of the magnesium isoelectronic sequence. For some elements of the sequence the present data are the only ones available.