Ground state and excitational properties of atoms

Abstract

We have carried out self-consistent electronic structure calculations on atoms, positive and negative ions and on X-ray transition energies by employing a generalized version of the Kohn-Sham theory which applies to anyN-electron eigenstate. This theory has recently been developed by Fritsche (Phys. Rev. B33, 3976 (1986)). As in the original Kohn-Sham version of density functional theory, it turns out that exchange and correlation can rigorously be described by a local energy-independent potential. The latter is in the present paper approximated by using correlation factors that have the form of a Gaussian or of a Lorentzian to the power 5/2. The width of these functions is determined via the familiar sum rule. We present results on atoms of the first three rows of the periodic table and on some heavier atoms. It is furthermore shown that the generalized Kohn-Sham theory can successfully be applied to multiplet states of free atoms. We discuss results on helium, carbon, oxygen and silicon. It may generally be stated that our approach yields a better overall agreement with the experimental data than any other approximation that has been used so far within density functional theory.