Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 22: Theoretical methods
O 22.9: Vortrag
Montag, 14. März 2011, 19:15–19:30, WIL C107
Exchange an Correlation effects in photoemission spectroscopy: from semiconductors to transition metal oxides — •Matteo Guzzo1, Matteo Gatti2, Francesco Sottile1, Pina Romaniello1, Fausto Sirotti3, John Rehr4, and Lucia Reining1 — 1LSI - ETSF, Ecole Polytechnique, Palaiseau, France — 2ETSF, Universidad del Pais Vasco, San Sebastian, Spain — 3Synchrotron Soleil, Gif-sur-Yvette, France — 4University of Washington, Seattle WA, USA
As a prototype of strongly-correlated systems, NiO has been extensively studied, however the origin of its gap is still under debate. Many-Body Perturbation Theory (MBPT) (with the one-particle Green’s function, aka the propagator of a particle, as key quantity) describes appropriately ab-initio photoemission gaps and spectra. GW approximation from MBPT includes dynamical correlation effects beyond H-F. The standard GW approach is not reliable on NiO since the Kohn-Sham band structure is too poor a starting point. COHSEX — a static approximation of GW — allows one to achieve full self-consistency, and to obtain a better starting point for the GW step. The COHSEX+GW result gives about 5 eV energy-gap, in good agreement with experiment and with other approaches beyond G0W0. An attempt to apply vertex corrections from TDDFT has shown no improvement in the spectrum. Here we focus on the effects of vertex corrections on quasiparticle energies and satellites and compare the cases of Si and NiO. The Cumulant Expansion approach is discussed as a possible alternative approach.