【Lecture】Electronic Band Structures from the GW Perspective

Published:2012-12-27 14:52:22 From:Editor hits：

Direct utilization of solar energy by photovoltaics and photo-catalysis is currently one of the most actively pursued frontiers in basic energy sciences. In particular, the direct photo-splitting of water to H₂ and O₂ is regarded as the “holy grail” for solar energy conversion. One of the greatest challenges is to find a semiconductor with a suitable band gap that allows efficient absorption of solar energy in the visible light regime, and appropriate valence and conduction band positions that match the redox potentials for water reduction and oxidation. Electronic band structures therefore play a crucial role in solar-energy conversion. Kohn-Sham density functional theory (KS-DFT) in the local or semi-local density approximations (LDA/GGA) has serious difficulty in describing electronic properties of extended systems. In this work, we apply many-body perturbation theory in the GW approximation to investigate electronic properties of several materials that are promising for solar energy conversion, including in particular, early transition metal dichalcogenides (TMDC) MX₂ (M=Zr, Hf, Mo and W, X=S and Se)[1,2], and alkaline tantalum oxides ATaO₃(A=Li, Na, K)[3]. In addition, we also perform a systematic investigation on the accuracy of the current first-principles methods for the prediction of absolute band positions, the energies of the valence band maximum (VBM) and conduction band minimum (CBM) with respect to the vacuum level by considering a set of prototypical semiconductors.

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