Coreless Thomas–Fermi models of atomic structure

We examine two atomic models which are based on Thomas–Fermi theory. In both cases we impose a shell structure by spatially partitioning the atom into zones. In the coreless Thomas–Fermi model we define two zones corresponding to the core and outer electrons. In the shell constrained Thomas–Fermi model we use one zone for each occupied shell in the atom. In both cases we obtain the full atomic densities by combining a ‖1s‖2 hydrogenic description of the core electrons with a Thomas–Fermi treatment of the outer electrons. The ionization potentials and atomic properties computed from both models are substantially more accurate than the corresponding values obtained from the original Thomas–Fermi method. The shell constrained model leads to an effective description of atomic valence shells which may be useful as a starting point for a density functional theory of molecular structure.