Comparison of Spherical Cell, OPW, and APW Methods for Hyperfine Contact Densities

Abstract

The spherical cell, OPW, and APW methods for the determination of the direct hyperfine contact density PFd are compared by means of explicit calculations for lithium metal. Serious deficiencies of the first two methods are discussed. In particular the OPW method is found to converge very slowly for the absolute value of PFd, although it predicts relative changes in PFd due to changes in atomic volume reasonably well. The Fermi level density of states, another quantity which affects the Knight shift, is also considered.