Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites
Bibliographic record
Abstract
Abstract Anharmonicity and disorder are ubiquitous in the physics of perovskites and give rise to a variety of unique phenomena observed in scattering and spectroscopy experiments with profound consequences for device applications. Several of these phenomena still lack interpretation from a first-principles perspective. Recently, the concept of polymorphism has been introduced in calculations of perovskite compounds, yielding substantial improvements in describing their electronic and structural properties. However, hitherto no approach is available to account for anharmonicity and polymorphism in the phonon dynamics and electron-phonon couplings. Here, we develop a unified framework for the treatment of both relying on the special displacement method. Combining the self-consistent phonon theory of Hooton and the Allen-Heine theory of electron-phonon renormalized band structures, we demonstrate our approach for temperature-dependent band gaps of oxide and halide cubic perovskites, obtaining unprecedented agreement with experiments. We also uncover that polymorphism in halide perovskites induces phonon bunching and overdamping that lead to vibrational dynamics far from the ideal phonon picture, consistent with neutron scattering measurements. Moreover, our results suggest that accurate band gap predictions require corrections arising from polymorphism, spin-orbit coupling, hybrid functionals, and electron-phonon coupling. The present method provides the basis for investigating electron-phonon couplings in strongly anharmonic materials.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".