Empirical band calculations of the optical properties of d - band metals. III. Rh and Pd

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 ω≤25 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.