The article discusses the development of atomic reference data for electronic structure calculations, focusing on the generalized Kohn-Sham theory and various approximations like LDA, LSD, RLDA, and ScRLDA. The calculations are limited to the ground-state electronic configurations of the first 92 neutral atoms and singly-charged cations of the periodic table.
The authors used four independently developed codes to perform the calculations, which were modified to achieve a target accuracy of 1 microHartree in total energy. The local-density approximation (LDA) was used with the Vosko, Wilk, and Nusair (VWN) functional, which is a fit to the Ceperley-Alder electron gas study and reproduces the random-phase-approximation (RPA) results for a uniform electron gas.
The choice of a radial grid is crucial for obtaining accurate numerical solutions of the integro-differential equations of density-functional theory. The codes used different grid choices, including exponentially increasing grids, grids with a change of variable technique, and grids that are nearly linear near the origin and exponentially increasing at larger radii.
The calculations used the 1986 CODATA recommended value for α-1, which has changed in more recent compilations of fundamental constants. The updated values for α-1 have a slight impact on the total energy and 1s Kohn-Sham eigenvalue in the RLDA approximation, with the shift in the direction of smaller binding energies.
Keywords: exchange-correlation, electronic structure, density-functional, relativistic corrections, electron gas
