Resumenes de las Charlas Invitadas
All-electron GW RPA applied to the electronic structure of materials
S. Lebègue, B. Arnaud1, M. Alouani
IPCMS, UMR 7504 du CNRS, 23 rue du Loess, 67037 Strasbourg, France, EU
1GMCM, campus de Beaulieu, 35042 Rennes Cedex, France, EU
Abstract
The GW approximation based on an all-electron Projector Augmented-Wave (PAW) method has been
developed to compute the quasiparticle properties of materials. Within this approach, the
self-energy is a product of the one-particle Greens function G and the dynamically screened
interaction W computed within the random phase approximation (RPA). Starting from the calculated
local density approximation (LDA) ground state, the LDA eigenvalues are corrected by treating the
difference between the self-energy and the exchange-correlation potential as a perturbation. The
calculated quasiparticle energies obtained by means of this procedure are, generally, in good
agreement with experiment. It is surprizing, however, that the quasiparticle energies are found to
be neither sensitive to the scheme used for decoupling core and valence electrons nor to the
different type of plasmon-pole models used to produce the dynamically screened interaction W. The
quasiparticle energies are then used to compute the macroscopic dielectric function including both
local-field and excitonic (electron-hole interaction) effects. The standard procedure for including
these effects in the calculation of the dielectric function consists in solving the so called
Bethe-Salpeter equation. This approach has been applied to different semiconductors and insulators,
and it has been shown that the inclusion of electron-hole attraction is necessary for a detailed
comparison of the theoretical and experimental optical spectra.
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