Spinor
G
W
/Bethe-Salpeter calculations in BerkeleyGW: Implementation, symmetries, benchmarking, and performance
G
W
/Bethe-Salpeter calculations in BerkeleyGW: Implementation, symmetries, benchmarking, and performance
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Computing the
G
W
quasiparticle band structure and Bethe-Salpeter equation (BSE) absorption spectra for materials with spin-orbit coupling have commonly been done by treating
G
W
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
G
W
/
BSE
. Such calculations have only recently become available, in particular for the BSE. We have implemented this approach in the plane-wave pseudopotential
G
W
/
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
Bi
2
Se
3
. 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
G
W
/
BSE
captures the large spin-orbit splitting of peaks in the spectrum. For the prototypical topological insulator
Bi
2
Se
3
, we find a drastic change in the low-energy band structure compared to that of DFT, with the spinorial treatment of the
G
W
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
G
W
/
BSE
calculations and perturbative approaches to SOC. This work aims to spur further development of spinor
G
W
/
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.
G
W
quasiparticle band structure and Bethe-Salpeter equation (BSE) absorption spectra for materials with spin-orbit coupling have commonly been done by treating
G
W
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
G
W
/
BSE
. Such calculations have only recently become available, in particular for the BSE. We have implemented this approach in the plane-wave pseudopotential
G
W
/
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
Bi
2
Se
3
. 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
G
W
/
BSE
captures the large spin-orbit splitting of peaks in the spectrum. For the prototypical topological insulator
Bi
2
Se
3
, we find a drastic change in the low-energy band structure compared to that of DFT, with the spinorial treatment of the
G
W
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
G
W
/
BSE
calculations and perturbative approaches to SOC. This work aims to spur further development of spinor
G
W
/
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.
Date Issued
2022-09-15
Date Acceptance
2022-09-06
Citation
Physical Review B, 2022, 106 (11), pp.1-17
ISSN
2469-9950
Publisher
American Physical Society (APS)
Start Page
1
End Page
17
Journal / Book Title
Physical Review B
Volume
106
Issue
11
Copyright Statement
©2022 American Physical Society
Identifier
http://dx.doi.org/10.1103/physrevb.106.115127
Publication Status
Published
Article Number
115127
Date Publish Online
2022-09-15