Screened KKR-Green's-function method for layered systems

A Green's-function method for layered systems based on screened Korringa-Kohn-Rostoker structure constants is presented. The screened structure constants are calculated in real space and the interlayer structure constants are obtained by a two-dimensional Fourier transform. As reference potentials we use repulsive muffin-tin and atomic-sphere potentials of various height. Performing test calculations for Cu(001) slabs, we demonstrate that for the angular momentum decomposed local charges a typical accuracy of 10^-3 electrons can be obtained, so that for practical applications the screening approximation can be used without loss of numerical accuracy. This precision can only be obtained if the screened structure constants include coupling to next nearest neighbors and if the reference potentials are sufficiently repulsive. It is demonstrated in slab calculations that the numerical effort scales linearly with the number of layers, allowing accurate, self-consistent calculations for very large systems.