Correlation Energies of Some He- and Ne-Like Systems

A calculation of correlation energies of some He-like and Ne-like ions is presented. In the calculation the experimental values and the relativistic corrections to the total energies are used. The Hartree-Fock energy for ${\mathrm{Al}}^{+3\mathrm{}}$ is calculated using analytic wave functions. A short discussion of the relativistic corrections and of a semiempirical formula for the correlation energies in atoms and ions is given.