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Abstract
We present an approach to calculate the optical absorption spectra that combines the quasiparticle selfconsistent GW method [Phys. Rev. B 76, 165106 (2007)] for the electronic structure with the solution of the ladder approximation to the BetheSalpeter equation for the macroscopic dielectric function. The solution of the BetheSalpeter equation has been implemented within an allelectron framework, using a linear muffintin orbital basis set, with the contribution from the nonlocal selfenergy to the transition dipole moments (in the optical limit) evaluated explicitly. This approach addresses those systems whose electronic structure is poorly described within the standard perturbative GW approaches with densityfunctional theory calculations as a starting point. The merits of this approach have been exemplified by calculating optical absorption spectra of a strongly correlated transition metal oxide, NiO, and a narrow gap semiconductor, Ge. In both cases, the calculated spectrum is in good agreement with the experiment. It is also shown that for systems whose electronic structure is welldescribed within the standard perturbative GW, such as Si, LiF, and h−BN, the performance of the present approach is in general comparable to the standard GW plus BetheSalpeter equation. It is argued that both vertex corrections to the electronic screening and the electronphonon interaction are responsible for the observed systematic overestimation of the fundamental band gap and spectrum onset.
Original language  English 

Article number  034603 
Number of pages  12 
Journal  Physical Review Materials 
Volume  2 
Issue number  3 
DOIs  
Publication status  Published  16 Mar 2018 
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R1520TSL: CCP Flagship: Quasiparticle SelfConsistent GW for NextGeneration Electronic Structure
21/04/2015 → …
Project: Research