Additional symmetry for the electronic shell in its ground state and many-electron effects

The additional symmetry for the properties related to the ground state of t he atom is considered taking into account many-electron effects. Calculatio ns of the I-4f, I-3d, I-2p, I-3p binding energies, 4f(N-1)5d - 4f(N) system differences and 2p, 3p electron affinities in the second order of perturba tion theory and in the configuration interaction approximation have been pe rformed for the ground configurations with one open shell. The analysis of separate many-electron corrections for these quantities and their variation along the sequences of atoms and ions shows that the main corrections main tain the considered symmetry.