Density functionals from models of the electronic charge density

The well known Thomas-Fermi theory with its subsequent development, provides a local density functional in terms of powers of the free electron gas parameter rhosup(1/3). For spherically symmetric charge densities, additional terms including 1/r, 1/r2, delta/deltar and delta2/deltar2 should be studied. The way they arise from the study of charge densities and the results that could be expected with their use, are analyzed in the present paper. (orig.)