Pd2Si: unoccupied one - particle states and white line in L2,3 - edge absortion spectra

The persistence of a pronounced resonance (white line) near the L2,3 absorption threshold on passing from pure Pd to Pd2Si has been investigated by a theoretical calculation of the photoabsorption spectra. The single-particle approximation with states derived from the (local) density-functional ground-state potential was used. The self-consistent band structure problem was solved by the linear muffin tin orbital (LMTO) method in the atomic-sphere approximation (ASA). Our results indicate that many-body effects are not needed in order to explain the presence of the white line at the L2,3 edge. In Pd2Si it arises from the Pd 4d-Si 3p antibonding states a few eV above the Fermi level. These states are also responsible for the shape of the L1 edge. Moreover, they provide an explanation of recent bremsstrahlung isochromat spectra.