Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.125: Poster

Tuesday, March 15, 2011, 18:30–22:00, P4

Band convergence of all-electron GW calculations: the extreme case of ZnO — •Christoph Friedrich, Mathias C. Müller, and Stefan Blügel — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Recently, Shih et al. [1] presented a new one-shot GW calculation for the band gap of wurtzite ZnO based on the pseudopotential approach. They showed that a proper convergence with respect to the number of bands used in the construction of the self-energy yields a band gap that is very close to the experimental value of 3.6 eV. This is in contrast to previous all-electron calculations where band gaps in the range 2.12–2.44 eV have been found [2]. In this work we present a GW calculation for ZnO that is based on the all-electron full-potential linearized augmented-plane-wave (FLAPW) method [3]. We obtain a band gap that is much larger than that of the previous all-electron calculations, but still smaller than that of Ref. 1. We go beyond their approach in two respects: we neither employ the pseudopotential nor the plasmon-pole approximation. Apart from the band convergence we also discuss the linearization error for high-lying states and how to eliminate it with local orbitals. Our results show that the band convergence is a very serious issue in the GW approach. ZnO is an extreme case in this respect. [1] B.-C. Shih et al., Phys. Rev. Lett. 105, 146401 (2010). [2] M. Usuda et al., Phys. Rev. B 66, 125101 (2002); M. Shishkin and G. Kresse, ibid. 75, 235102 (2007); F. Fuchs et al., ibid. 76, 115109 (2007). [3] C. Friedrich et al., Phys. Rev. B 81, 125102 (2010).