Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 49: Ab-initio approaches to excitations in condensed matter II
O 49.3: Vortrag
Donnerstag, 26. März 2009, 11:00–11:15, SCH 251
Transforming Nonlocality into a Frequency Dependence: A Shortcut to Spectroscopy — •Matteo Gatti1,2,3, Valerio Olevano1,4, Ilya Tokatly1,3, and Lucia Reining1,2 — 1European Theoretical Spectroscopy Facility (ETSF) — 2LSI - Ecole Polytechnique, Palaiseau, France — 3Universidad del País Vasco, San Sebastian, Spain — 4Institut Néel, Grenoble, France
Measurable spectra are often derived from contractions of many-body Green's functions. In this way, one calculates hence more information than needed. Here we present and illustrate an in principle exact approach to construct effective potentials and kernels for the direct calculation of electronic spectra. In particular, a dynamical but local and real potential yields the spectral function needed to describe photoemission. We discuss for model solids the frequency dependence of this photoemission potential stemming from the nonlocality of the corresponding self-energy. We also show that our approach leads to a very short derivation of a kernel of time-dependent (current-)density functional theory that is known to well describe absorption and energy-loss spectra of a wide range of materials.