REOS — A program for relaxed-orbital oscillator strength calculations Original Research Article

A spontaneous decay of an excited atomic state leads to a rearrangement of the spatial electron distribution in the atom. This redistribution concerns the entire electronic cloud and not only the active electron in an atomic transition. For many-electron atoms, rearrangement effects are naturally included if the electronic wavefunctions of the initial and final states are determined independently. The separate optimization of the atomic states, however, yields two sets of one-electron orbitals which are not orthogonal to each other. This incomplete orthogonality also influences the calculation of transition amplitudes since, additionally, many small contributions arise from the radial overlap of electrons of different subshells which have the same symmetry.In the framework of the GRASP92 atomic structure package we describe a program for the computation of oscillator strengths and Einstein A and B coefficients. The program is based on a determinant representation of the atomic states and allows for incomplete orthogonal radial orbital functions for the initial and final states. For large lists of configuration state functions, this module also facilitates the computation of transition arrays since the initial and final states need not to be determined in the same run.