Kavli Affiliate: Jeffrey B. Neaton
| First 5 Authors: Jonah B. Haber, Diana Y. Qiu, Felipe H. da Jornada, Jeffrey B. Neaton,
| Summary:
We introduce a maximally-localized Wannier function representation of Bloch
excitons, two-particle correlated electron-hole excitations, in crystalline
solids, where the excitons are maximally-localized with respect to an average
electron-hole coordinate in real space. As a proof-of-concept, we illustrate
this representation in the case of low-energy spin-singlet and triplet excitons
in LiF, computed using the ab initio Bethe-Salpeter equation approach. We
visualize the resulting maximally-localized exciton Wannier functions (MLXWFs)
in real space, detail the convergence of the exciton Wannier spreads, and
demonstrate how Wannier-Fourier interpolation can be leveraged to obtain
exciton energies and states at arbitrary exciton crystal momenta in the
Brillouin zone. We further introduce an approach to treat the long-range
dipolar coupling between singlet MLXWFs and discuss it in depth. The MLXWF
representation sheds light on the fundamental nature of excitons and paves the
way towards Wannier-based post-processing of excitonic properties, enabling the
construction of ab initio exciton tight-binding models, efficient interpolation
of the exciton-phonon vertex, the computation of Berry curvature associated
with exciton bands, and beyond.
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