Transition probabilities and oscillator strengths of E1 transitions in Fe XII and Fe XIV

Abstract

Non-orthogonal orbitals in the multiconfiguration Hartree–Fock approach are used to calculate line strengths, oscillator strengths and transition probabilities for E1 transitions among the fine-structure levels of the 3s 23p 3, 3s3p 4, 3s 23p 23d, 3s3p 33d, 3p 5 and 3s 23p3d 2 configurations in Fe XII and 3s 23p, 3s3p 2, 3s 23d, 3p 3, 3s3p3d, 3p 23d, 3s3d 2, 3p3d 2, 3s 24s, 3s 24p, 3s3p4s and 3s 24d configurations in Fe XIV. The lifetimes of excited levels belonging to these configurations of Fe XII and Fe XIV are also presented. An accurate representation of the levels has been obtained using spectroscopic and correlation radial functions. The wavefunctions exhibit large correlations and significant dependence of one-electron valence orbitals due to both the total and intermediate terms. The relativistic corrections are included through the one-body and two-body operators in the Breit–Pauli Hamiltonian. Progressively larger calculations are performed to check for important electron correlation contributions and for convergence of results. The atomic wavefunctions give excitation energies which are in close agreement with experiment. The present oscillator strengths and transition probabilities compare very well with previous large scale calculations.