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Weissker, Hans-Christian Huotari, Simo Bruneval, Fabien Sottile, Francesco Monaco, Giulio Krisch, Michael Olevano, Valerio Reining, Lucia Serrano Gutiérrez, Jorge 2024-01-30T12:26:38Z 2024-01-30T12:26:38Z 2006 Phys. Rev. Lett. 97, 237602 (2006) 0031-9007 https://uvadoc.uva.es/handle/10324/65321 10.1103/PhysRevLett.97.237602 23 Physical Review Letters 97 1079-7114 We present an investigation of the dynamic structure factor and of the dielectric function εM(Q,ω) 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. European Synchrotron Radiation Facility - ESRF European Union European Union - Marie Curie IEF IDRIS application/pdf eng American Physical Society info:eu-repo/semantics/openAccess Signatures of Short-Range Many-Body Effects in the Dielectric Function of Silicon for Finite Momentum Transfer info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion SI