Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 64: Focussed session: Theory and computation of electronic structure: new frontiers V (jointly with HL, DS)
O 64.4: Vortrag
Donnerstag, 17. März 2011, 12:15–12:30, TRE Phy
Ab initio calculations of electronic excitations: Collapsing spectral sums — •Arjan Berger1,2, Lucia Reining1,2, and Francesco Sottile1,2 — 1Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS, CEA-DSM, 91128 Palaiseau, France — 2European Theoretical Spectroscopy Facility (ETSF)
We present a method for the evaluation of electronic excitations of advanced materials by reformulating spectral sum-over-states expressions such that only occupied states appear. All empty states are accounted for by one effective energy. Thus we keep the simplicity and precision of the sum-over-states approach while speeding up calculations by more than an order of magnitude. We demonstrate its power by applying it to the GW method, where a huge summation over empty states appears twice (screening and self-energy). We show the precision bulk silicon and argon. We then use it to determine the band structure and optical spectrum of the technologically important oxide SnO2. We will also show how our approach can be used to develop exchange-correlation kernels for time-dependent density-functional theory that are both accurate and computationally efficient.