Abstract
Band-structure calculations for Rh and Pd have been performed by a second-principles approach using a combined interpolation scheme. From these bands the imaginary part of the dielectric function ε2 in the energy range ω25 eV has been calculated with full inclusion of momentum matrix elements and spin-orbit effects. The band-by-band decompositions of ε2 are presented, and structures are identified with transitions between specific bands in k space. Agreement with experiment is found to be good, and identifications are offered for the principal experimental structures. Furthermore, ε2 values assuming constant matrix elements for both direct and nondirect transitions have been calculated to assess the influence of the matrix elements and to test the direct-transition model.