ALL-ELECTRON STUDY OF GRADIENT CORRECTIONS TO THE LOCAL-DENSITY FUNCTIONAL IN METALLIC SYSTEMS

Using the all-electron linearized-augmented-plane-wave method, we calculate the effect of including gradient corrections to the exchange-correlation functional on the structural properties of the simple metal Al, transition metals Ta, W, and Pt, and noble metals Cu, Ag, Au. For all the systems studied, the local-density approximation (LDA) yields bond lengths that are too short and bulk moduli that are too large. The generalized gradient functional introduced by Perdew and Wang (PW91) yields corrections that are in the right direction (larger bond lengths and smaller bulk moduli), but it frequently overcompensates. The PW91 functional predicts the lattice constant of Cu and Ta more accurately than the LDA but yields values that are less accurate than the LDA for Ag, Pt, and Au. The PW91 functional predicts the bulk moduli of Al, Cu, Ag, Ta, and W more accurately than the LDA. © 1995 The American Physical Society.