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Excitonic Bloch equations from first principles
by Gianluca Stefanucci, Enrico Perfetto
Submission summary
| Authors (as registered SciPost users): | Gianluca Stefanucci |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202410_00048v1 (pdf) |
| Date submitted: | 2024-10-21 15:24 |
| Submitted by: | Stefanucci, Gianluca |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
The ultrafast conversion of coherent excitons into incoherent excitons, as well as the subsequent exciton diffusion and thermalization, are central topics in current scientific research due to their relevance in optoelectronics, photovoltaics and photocatalysis. Current approaches to the exciton dynamics rely on {\em model} Hamiltonians that depend on already screened electron-electron and electron-phonon couplings. In this work, we subject the state-of-the-art methods to scrutiny using the {\em ab initio} Hamiltonian for electrons and phonons. We offer a rigorous and intuitive proof demonstrating that the exciton dynamics governed by model Hamiltonians is affected by an overscreening of the electron-phonon interaction. The introduction of an auxiliary exciton species, termed the irreducible exciton, enables us to formulate a theory free from overscreening and derive the excitonic Bloch equations. These equations describe the time-evolution of coherent, irreducible, and incoherent excitons during and after the optical excitation. They are applicable beyond the linear regime, and predict that the total number of excitons is preserved when the external fields are switched off.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Author comments upon resubmission
thank you for handling our manuscript. We would also like to thank the Referees for the excellent reports, which have undoubtedly contributed to improve the clarity of the presentation.
With this resubmission we provide a pdf containing the reply to both Referees (reply.pdf), and a new version of the manuscript.
Sincerely, Gianluca Stefanucci and Enrico Perfetto
List of changes
1) We clarify that excitons and particle-hole pairs are treated on equal footing at the end of the introduction
2) We clarify that the electronic band indices are spin-orbital indices at the beginning of Section 2.1
3) We discuss the Pauli blocking factors at the end of Section 2.3
4) We clarify the limitations of the theory at the end of Section 2.3
5) We discuss the relation between the polarizations and the absorption spectrum at the beginning of Section~3
6) We clarify that both the reducible and irreducible exciton-phonon coupling are essential, though relevant in different regimes at the beginning of Section 6
7) We discuss the long time limit solution of the XBE at the end of Section 6
Current status:
Reports on this Submission
Report
I think the authors have adequately addressed the comments made by reviewers in the revised version of the manuscript. Therefore, I have no further comments and I recommend the article for publication.
Recommendation
Publish (meets expectations and criteria for this Journal)