Relativistic calculations to assess the ability of the generalized gradient approximation to reproduce trends in cohesive properties of solids

Abstract

We have performed density functional calculations on solids in four columns of the periodic table, containing the elements Ca, Sr, Ba, As, Sb, Bi, Cu, Ag, Au, Ce, and Th. In order to get a meaningful estimation of the quality of the generalized gradient approximation (GGA) to predict trends within a column, as few other approximations were made as possible. Most notably, the spin-orbit effect has not been neglected. In many cases there appears to be a tendency towards underbinding on going down in a column. This is most pronounced in the noble metal column Cu, Ag, Au. The overall performance of the GGA is still reasonable. The mean absolute errors of the calculated cohesive energy, lattice parameter, and bulk modulus are 0.35 eV, 0.10 bohr, and 0.15 Mbar, respectively. Nonnegligible contributions of the spin-orbit coupling are found for the cohesive energy and the lattice parameter of Au and in particular Bi.