Bond versus charge disproportionation and nature of the holes in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>s</mml:mi><mml:mo>−</mml:mo><mml:mi>p</mml:mi></mml:mrow><mml:mo> </mml:mo><mml:mrow><mml:mi>A</mml:mi><mml:mi>B</mml:mi><mml:msub><mml:mi>X</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> perovskites
Bibliographic record
Abstract
We use density functional theory methods to study the electronic structures of a series of $s\text{\ensuremath{-}}p$ cubic perovskites, $AB{X}_{3}$: the experimentally available $\mathrm{Sr}\mathrm{Bi}{\mathrm{O}}_{3}, \mathrm{Ba}\mathrm{Bi}{\mathrm{O}}_{3}, \mathrm{Ba}\mathrm{Sb}{\mathrm{O}}_{3}, \mathrm{Cs}\mathrm{Tl}{\mathrm{F}}_{3}$, and $\mathrm{Cs}\mathrm{Tl}{\mathrm{Cl}}_{3}$, as well as the hypothetical $\mathrm{Mg}{\mathrm{PO}}_{3}, \mathrm{Ca}\mathrm{As}{\mathrm{O}}_{3}, \mathrm{Sr}\mathrm{Sb}{\mathrm{O}}_{3}$, and $\mathrm{Ra}\mathrm{Mc}{\mathrm{O}}_{3}$. We use tight-binding modeling to calculate the interatomic hopping integrals ${t}_{sp\ensuremath{\sigma}}$ between the $B\phantom{\rule{4pt}{0ex}}s$ and $X\phantom{\rule{4pt}{0ex}}p$ atomic orbitals and charge-transfer energies $\mathrm{\ensuremath{\Delta}}$, which are the two most important parameters that determine the low-energy electron and hole states of these systems. Our calculations elucidate several trends in ${t}_{sp\ensuremath{\sigma}}$ and $\mathrm{\ensuremath{\Delta}}$ as one moves across the periodic table, such as the relativistic energy lowering of the $B\phantom{\rule{4pt}{0ex}}s$ orbital in heavy $B$ cations, leading to strongly negative $\mathrm{\ensuremath{\Delta}}$ values. Our results are discussed in connection with the general phase diagram for $s\text{\ensuremath{-}}p$ cubic perovskites proposed by Khazraie et al. [Phys. Rev. B 98, 205104 (2018)], who find the parent superconductors $\mathrm{Sr}\mathrm{Bi}{\mathrm{O}}_{3}$ and $\mathrm{Ba}\mathrm{Bi}{\mathrm{O}}_{3}$ to be in the regime of negative $\mathrm{\ensuremath{\Delta}}$ and large ${t}_{sp\ensuremath{\sigma}}$. Here, we explore this further and search for different materials with similar parameters, which could lead to the discovery of new superconductors. Also, some considerations are offered regarding a possible relation between the physical properties of a given $s\text{\ensuremath{-}}p$ compound (such as its tendency to bond disproportionate and the maximal achievable superconducting transition temperature) and its electronic structure.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.011 | 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".