Hund's rule and the Z expansion for the energy,electron repulsion and electron nuclear attraction

A Z expansion is derived for the expectation values of the interelectronic repulsion energy and the electron-nuclear attraction energy in atomic states. The formalism, which is based on a non-relativistic hamiltonian, is applied to excited states in iso-electronic sequences. It appears that there are many cases where the state of the highest multiplicity has the larger expectation value for the interelectronic repulsion energy although it has a lower total energy.