Signatures of short-range many-body effects in the dielectric function of silicon for finite momentum transfer
|Title||Signatures of short-range many-body effects in the dielectric function of silicon for finite momentum transfer|
|Publication Type||Palaiseau Article|
|Author Address|| |
Weissker, HC (Reprint Author), Ecole Polytech, CNRS, UMR 7642, CEA,DSM,Lab Solides Irradies, F-91128 Palaiseau, France. Ecole Polytech, CNRS, UMR 7642, CEA,DSM,Lab Solides Irradies, F-91128 Palaiseau, France. European Synchrotron Radiat Facil, F-38043 Grenoble, France. CNRS, LEPES, UPR 11, F-38042 Grenoble, France. ETSF, Palaiseau, France.
|Weissker, H-C, Serrano, J, Huotari, S, Bruneval, F, Sottile, F, Monaco, G, Krisch, M, Olevano, V, Reining, L|
|Year of Publication||2006|
|Journal||Phys. Rev. Lett.|
We present an investigation of the dynamic structure factor and of the dielectric function epsilon(M)(Q,omega) of the prototypical semiconductor silicon for finite momentum transfer, combining inelastic x-ray scattering experiments and ab initio calculations. In contrast with optical spectra, for finite momentum transfer time-dependent density-functional theory in the adiabatic local-density approximation together with lifetime broadening describes the physics of valence excitations correctly. Major structures in the spectra, governed by short-range crystal and exchange-correlation local-field effects, are strongly influenced by a mixing of transitions of positive and negative energies, in striking difference to spectra for vanishing momentum transfer. This mixing gives rise to a pronounced Fano asymmetry.