Energies of Sr states with excited valence shell

Singly- and doubly-excited Sr states emerging upon excitation of the valence shell have been investigated. Only states with low values of the principal quantum numbern of the valence electrons have been considered: 5s4d, 5s5p, 5p ², 4d ² and 4d5p. These states have been treated by a perturbation theory based on the Dirac equations with model potential, the valence electrons interaction being considered as a perturbation. The zero-order approximation accounts for the main contributing interactions including the strong core potential screening. The applied calculation method was previously developed for highly-excited Rydberg states but its application also for states with lown was proved to be suitable.