We present an extension of the quasiparticle self-consistent GW approximation (QSGW) [T. Kotani, Phys. Rev. B 76, 165106 (2007)10.1103/PhysRevB.76.165106] to include vertex corrections in the screened Coulomb interaction W. This is achieved by solving the Bethe-Salpeter equation for the polarization matrix at all k points in the Brillouin zone. We refer to this method as QSGŴ. QSGW yields a reasonable and consistent description of the electronic structure and optical response, but systematic errors in several properties appear, notably a tendency to overestimate insulating band gaps, blueshift plasmon peaks in the imaginary part of the dielectric function, and underestimate the dielectric constant ϵ∞. A primary objective of this paper is to assess to what extent including ladder diagrams in W ameliorates systematic errors for insulators in the QSGW approximation. For benchmarking we consider about 40 well-understood semiconductors, and also examine a variety of less well-characterized nonmagnetic systems, six antiferromagnetic oxides, and the ferrimagnet Fe3O4. We find ladders ameliorate shortcomings in QSGW to a remarkable degree in both the one-body Green's function and the dielectric function for a wide range of insulators. New discrepancies with experiment appear, and a key aim of this paper is to establish to what extent the errors are systematic and can be traced to diagrams missing from the theory. One key finding of this work is to establish a relation between the band gap and the dielectric constant ϵ∞. Good description of both properties together provides a much more robust benchmark than either alone. We show how this information can be used to improve our understanding of the one-particle spectral properties in materials systems such as SrTiO3 and FeO.
Bibliographical noteFunding Information:
The authors would like to thank all those involved in the CCP flagship project: Quasiparticle Self-Consistent for Next-Generation Electronic Structure, especially S. Mckechnie for his help. We are grateful for support from the Engineering and Physical Sciences Research Council, under Grant No. EP/M011631/1. M.v.S. and D.P. were supported the Computational Chemical Sciences program within the Office of Basic Energy Sciences, U.S. Department of Energy under Contract No. DE-AC36-08GO28308. We are grateful to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC (Grant No. EP/P020194/1). The research was performed using computational resources sponsored by the Department of Energy's Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory. This research also used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC Award No. BES-ERCAP0021783.
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ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics