Momentum density calculations in solids using the Korringa-Kohn-Rostoker method

Abstract

A new method is presented for the efficient calculation of the momentum density rho (p) in Compton scattering and positron annihilation. It is based on the KKR method but avoids awkward integrations of spherical waves over the atomic polyhedron by making use of a plane wave basis. The method treats the positron and the electron on the same footing. The final results are simple and show clearly the relation between the high-momentum components in rho (p) and the plane wave components of the wavefunctions. The formulae are generalised to a lattice with a basis. Illustrative results are shown for Cu, viewed as a simple cubic lattice with four atoms per cell.