Photoemission spectra and band structures ofd-band metals. X. Relativistic momentum matrix elements

Band-structure calculations are performed to assess the magnitude of relativistic effects in angle-resolved photoemission. The specific case of normal emission from Ag(111) is considered using a combined interpolation scheme which incorporates spin-orbit coupling both within the $d$ bands and between the plane waves of the basis set. Detailed numerical results are presented for the momentum matrix elements in the nonrelativistic and relativistic cases for all the initial-state bands in both parallel and perpendicular polarization. The observability of relativistic effects in available and future experimental data is discussed.