A PERTURBATIONAL APPROACH TO OBTAIN HIGH ACCURACY WAVELENGTH, APPLIED TO THE SUPERSTRUCTURE CODE

A perturbational method for improving calculated energy levels of atomic elements (Z ≤ 30) at different ionization stages is presented. The method uses as a starting point the SUPERSTRUCTURE code developed at the University College London and uses scaled Thomas-Fermi potentials. The perturbation theory is applied up to the second order energy correction and introduces the contribution of the complete basis, including continuum states of the unperturbed hamiltonian. As an illustration the method is applied to the determination of some energy terms of the He-like oxygen ion