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    Université de Fribourg

    Ab initio many-body effects in TiSe₂: A possible excitonic insulator scenario from GW band-shape renormalization

    Cazzaniga, M. ; Cercellier, H. ; Holzmann, M. ; Monney, Claude ; Aebi, Philipp ; Onida, Giovanni ; Olevano, V.

    In: Physical Review B - Condensed matter and materials physics, 2012, vol. 85, no. 19, p. 195111

    We present both theoretical ab-initio results within the Hedin's GW approximation and experimental angle-resolved photoemission and scanning tunneling spectroscopy measurements on TiSe₂. With respect to the density-functional Kohn-Sham metallic picture, the many-body GW self-energy leads to a ≈0.2-eV band-gap insulator consistent with our STS spectra at 5 K. The highest valence and the lowest...

    Université de Fribourg

    Valence band structure of the Si(331)-(12 × 1) surface reconstruction

    Battaglia, Corsin ; Schwier, Eike Fabian ; Monney, Claude ; Didiot, Clément ; Mariotti, Nicolas ; Gaál-Nagy, Katalin ; Onida, Giovanni ; Garnier, Michael Gunnar ; Aebi, Philipp

    In: Journal of Physics: Condensed Matter, 2011, vol. 23, no. 13, p. 135003

    Using angle-resolved photoelectron spectroscopy we investigate the electronic valence band structure of the Si(331)-(12 × 1) surface reconstruction for which we recently proposed a structural model containing silicon pentamers as elementary structural building blocks. We find that this surface, reported to be metallic in a previous study, shows a clear band gap at the Fermi energy, indicating...

    Université de Fribourg

    Structure and stability of the Si(331)-(12×1) surface reconstruction investigated with first-principles density functional theory

    Battaglia, Corsin ; Onida, Giovanni ; Gaál-Nagy, Katalin ; Aebi, Philipp

    In: Physical Review B: condensed matter and materials physics, 2009, vol. 80, no. 21, p. 214102

    We recently proposed a structural model for the Si(331)-(12×1) surface reconstruction containing silicon pentamers and adatoms as elementary structural building blocks. Using first-principles density functional theory we here investigate the stability of a variety of adatom configurations and determine the lowest-energy configuration. We also present a detailed comparison of the energetics...