ABSTRACT
A consequence of the central field approximation, which we used in Chapters 4 and 5, is that an atom with an incomplete shell is a highly degenerate system with respect to energy. For the shell nℓ there are g = 2(2ℓ + 1) orbitals (states) with the same energy. If the shell is occupied by N ≤ g electrons, then () ( g N ) = g ! N!(g − N)! https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429493645/749bab20-4a79-4f5a-8c66-d9e9a36a87b9/content/eq439.tif"/>
