ABSTRACT
Accurate calculations of the properties of atoms are enormously difficult. There are two sources of this difficulty: the Coulomb interaction between the electrons, and the spin-orbit interaction between the electron spins and the electric fields in the atom. This chapter describes the general features of atomic structure and outlines briefly how one does calculations. The spin-orbit interaction can be regarded as a weak perturbation in the lighter atoms, and to a first approximation it can be neglected entirely. The general features of the self-consistent potential can be determined by a semi classical approach due to Thomas and Fermi. The Fermi-Thomas method is based on the observation that in a very large atom most electrons have a large kinetic energy and therefore varies slowly in space compared with the rate of spatial variation of the electronic wave functions. Eventually one must be careful to include the effects of the nuclear motion.
