All-Electron Study of Gradient Corrections to the Local Density Functional in Metallic Systems

Abstract

Using the all-electron Linearized Augmented Plane Wave (LAPW) 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, 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 over compensates, particularly for the heavier elements. The PW 91 functional predicts the lattice constant and bulk modulus of Al and Cu more accurately than the LDA but yields values thatare less accurate than the LDA for W, Pt, Au.