Knowledge Bank

With the ''Laboratory of Molecular Structure and Spectra-Chicago'' self-consistent field atomic program, accurate SCF energies are computed for a variety of atomic systems. These systems include the ground state and all the excited states of the lowest configuration for the nuclei from $Z=2$ to $Z=36$ with 2 to 18 electrons. Negative ions are not considered. The total energies of these systems are then compared with the experimental total energies and, by subtraction of the estimated relativistic correction, the correlation energy is obtained (within a few percent of accuracy). The dependency of the correlation energy from the Z number, the number of electrons, the angular and radial electronic distribution, the number and kind of electron spin, emerges very simply. ''Irregularity in the experimental ionization potentials are explained with the aid of the correlation energy.''