Algorithms for Korringa-Kohn-Rostoker electronic structure calculations in any Bravais lattice

Abstract

We present some algorithms for improvements of band theory calculations based on the Korringa-Kohn-Rostoker method and on the coherent potential approximation, in the cases of ordered metals and random alloys. The purpose of our work was to develop a code flexible enough to deal on equal footing with any lattice geometry. The algorithms proposed are designed to achieve an arbitrary accuracy and to minimize the required computational efforts. In particular, we describe (i) an efficient and accurate method for the calculation of the KKR structure constants, and (ii) an adaptive method for the Brillouin zone integration. These algorithms have been tested for a free-electron Green's function and by explicit calculations for a number of systems and, when possible, discussed in comparison with other methods. Ab initio calculations for hexagonal close packed and face centered cubic Ti and for ${\mathrm{Cu}}_{0.75}$-${\mathrm{Pt}}_{0.25}$ random alloys are presented.