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Methods

The wave functions for both initial and final states were determined using the nonrelativistic multiconfgiurational Hartree-Fock (MCHF) approach. The wave functions were built from a basis of one-electron spin-orbital functions and were expanded in terms of configuration state functions (CSF). In order to keep the calculations in reasonable bounds the method of Restrictive Active Space (RAS) was applied. The size of the active sets (characterized by the largest principal quantum number, n) was incremented until a convergence of both the LS transition energy and the two forms of LS line strength were achieved.

In the Breit-Pauli approximation, terms for a specific J value interact, and this requires that mixing effects between terms be considered. The traditional MCHF method was modified to permit a simultaneous optimization of the weighted energy expressions derived from multiple terms. This allowed a single orbital set to represent a choice of terms with strong relativistic mixing. Then, by diagonalization of the Breit-Pauli Hamiltonian a few selected eigenvalues were determined. The bi-orthonormal method was applied to compute the transition data.



2001-10-11