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O: Fachverband Oberflächenphysik
O 59: Poster Session II (Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: arrays; Nanostructures at surfaces: Wires, tubes; Nanostructures at surfaces: Other; Plasmonics and nanooptics; Metal substrates: Epitaxy and growth; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsoprtion of organic / bio molecules; Metal substrates: Adsoprtion of inorganic molecules; Metal substrates: Adsoprtion of O and/or H; Metal substrates: Clean surfaces; Density functional theory and beyond for real materials)
O 59.112: Poster
Mittwoch, 24. März 2010, 17:45–20:30, Poster B1
Calculation of GW electronic structure for large systems : application to amorphous silica — •David Waroquiers1,2, Matteo Giantomassi1,2, Gian-Marco Rignanese1,2, and Xavier Gonze1,2 — 1Unité de Physico-Chimie et de Physique des Matériaux (PCPM), Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium. — 2European Theoretical Spectroscopy Facility (ETSF)
For accurate ab initio electronic structure calculations, many-body perturbation theories such as GW approximation or Bethe-Salpeter equation are essential. Up to recently, these methods could only be applied to small systems because of the large computational cost of these techniques. New theoretical and algorithmic developments (extrapolar method to reduce the number of empty states needed in GW calculations [1], band parallelism [2], and PAW formalism [3]) now enable us to perform GW calculations in supercells with more than 50 atoms within a reasonable amount of CPU time.
We applied these methods [4] to study the electronic structure of amorphous silica. More than twenty different configurations have been considered, each of them being obtained by relaxing 72-atom supercells at fixed volume. Then, different charged states of atomic hydrogen have been incorporated and relaxed in the larger voids of the systems. Defect energy levels have been calculated within the GW approximation.
[1] F. Bruneval and X. Gonze, Phys. Rev. B 78 (2008) 085125.
[2] X. Gonze et al., Comput. Phys. Comm. 180 (2009) 2582.
[3] M. Torrent et al., Comput. Mater. Sc. 42 (2008) 337.
[4] As implemented in the version 6 of ABINIT (http://www.abinit.org).