Screened KKR with hard-core potentials

We developed a self-consistent screened-Korringa-Kohn-Rostoker (KKR) method in an ab initio tight-binding formulation. The reduction in numerical effo rt in comparison with that required for the standard KKR method is achieved by the choice of a suitable reference system. Following the idea of Zeller et al. (1995, Phys. Rev. B, 52, 8807), reference systems with repulsive mu ffin-tin potentials of constant height are considered. This paper is dedica ted to reference potentials of infinite height, so-called hard core potenti als. It will be demonstrated that the advantage of the analytical solution to the scattering problem is accompanied by a reduced accuracy of the scree ned KKR method for close-packed hard spheres. To overcome this problem, we consider hard spheres with a reduced diameter. The best results also in com parison with reference potentials of finite height are obtained using hard spheres with a radius reduced to about 80% of the muffin-tin value.