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Spinor GW /Bethe-Salpeter calculations in BerkeleyGW: Implementation, symmetries, benchmarking, and performance

Barker, BA and Deslippe, J and Lischner, J and Jain, M and Yazyev, OV and Strubbe, DA and Louie, SG (2022) Spinor GW /Bethe-Salpeter calculations in BerkeleyGW: Implementation, symmetries, benchmarking, and performance. In: Physical Review B, 106 (11).

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Official URL: https://doi.org/10.1103/PhysRevB.106.115127


Computing the GW quasiparticle band structure and Bethe-Salpeter equation (BSE) absorption spectra for materials with spin-orbit coupling have commonly been done by treating GW corrections and spin-orbit coupling (SOC) as separate perturbations to density-functional theory. However, accurate treatment of materials with strong spin-orbit coupling (such as many topological materials of recent interest, and thermoelectrics) often requires a nonperturbative approach using spinor wave functions in the Kohn-Sham equation and GW/BSE. Such calculations have only recently become available, in particular for the BSE. We have implemented this approach in the plane-wave pseudopotential GW/BSE code BerkeleyGW, which is highly parallelized and widely used in the electronic-structure community. We present reference results for quasiparticle band structures and optical absorption spectra of solids with different strengths of spin-orbit coupling, including Si, Ge, GaAs, GaSb, CdSe, Au, and Bi2Se3. The calculated quasiparticle band gaps of these systems are found to agree with experiment to within a few tens of meV. SOC splittings are found to be generally in better agreement with experiment, including quasiparticle corrections to band energies. The absorption spectrum of GaAs is not significantly impacted by the inclusion of spin-orbit coupling due to its relatively small value (0.2 eV) in the Λ direction, while the absorption spectrum of GaSb calculated with the spinor GW/BSE captures the large spin-orbit splitting of peaks in the spectrum. For the prototypical topological insulator Bi2Se3, we find a drastic change in the low-energy band structure compared to that of DFT, with the spinorial treatment of the GW approximation correctly capturing the parabolic nature of the valence and conduction bands after including off-diagonal self-energy matrix elements. We present the detailed methodology, approach to spatial symmetries for spinors, comparison against other codes, and performance compared to spinless GW/BSE calculations and perturbative approaches to SOC. This work aims to spur further development of spinor GW/BSE methodology in excited-state research software and enables a more accurate and detailed exploration of electronic and optical properties of materials containing elements with large atomic numbers.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to the Authors.
Keywords: Absorption spectra; Absorption spectroscopy; Antimony compounds; Atoms; Benchmarking; Bismuth compounds; Cadmium compounds; Computation theory; Density functional theory; Electronic structure; Energy gap; Excited states; Gallium arsenide; Germanium compounds; Gold compounds; II-VI semiconductors; III-V semiconductors; Light absorption; Optical properties; Semiconducting gallium; Wave functions, Bethe-Salpeter; Bethe-Salpeter equation; Density-functional-theory; Nonperturbative; Performance; Quasiparticle band structures; Spin-orbit couplings; Spinors; Thermoelectric; Topological materials, Selenium compounds
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 13 Oct 2022 05:06
Last Modified: 13 Oct 2022 05:06
URI: https://eprints.iisc.ac.in/id/eprint/77290

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