Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 43: Theory of electronic structure
HL 43.1: Vortrag
Donnerstag, 29. März 2007, 14:00–14:15, H14
Analysis of core-valence linearization in G0W0 calculation — •Xinzheng Li1, Ricardo Gomez-Abal1, Claudia Ambrosch-Draxl2, and Matthias Scheffler1 — 1Fritz-Haber-Insitut der Max-Planck-Gesellschaft, D-14195, Berlin — 2Department of Material Physics, A-8700, Leoben
In recent years, the GW approach, typically applied as the first order correction to the Kohn-Sham (KS) eigenenergies (G0W0 approximation), has achieved great success in describing the single-particle excitations in weakly correlated semiconductors and insulators. For implementation simplicity and computational efficiency, most of the existing codes are based on the pseudopotential (PP) method, in which the self-energy is only calculated from the (pseudo-)valence states. It is already well-known in DFT that such a linear treatment of the core-valence exchange-correlation interaction is not always valid. Non-linear core corrections have to be added in such cases. While within G0W0-PP, core-valence interaction can only be included at the KS level, its results always show better agreement with experiment than the all-electron calculations available so far. In this talk, we analyze the reasons for this disturbing discrepancy and the validity of the “core-valence linearization” in the G0W0-PP scheme. Calculations are performed using our newly developed all electron G0W0 code, based on the Wien2k implementation of the FP-(L)APW+lo method. We compare our all-electron results with those obtained by computing the self-energy from the valence states only as well as with G0W0-PP calculations for selected materials (e.g. Si, GaAs, NaCl, ...).