Electron-phonon coupling in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mtext>C</mml:mtext><mml:mrow><mml:mn>60</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>using hybrid functionals
Bibliographic record
Abstract
The calculations of the electron-phonon coupling in ${\text{C}}_{60}$ molecules are analyzed in the context of hybrid functionals within the density-functional theory (DFT) approach. We find that increasing the contribution of the exchange energy calculated with a Fock operator in a functional from 0 to 30% has little impact on structural properties and phonon frequencies, but it generates a strong increase of the total electron-phonon coupling $(\ensuremath{\sim}40\mathrm{%})$. The resulting electron-phonon couplings for each vibrational mode are in better agreement with experimental data. In particular, the ${H}_{g}$ vibrational modes contribution to the total coupling increased from 67 to 94 meV, which compares favorably with the most recent experimental value of 97 meV. With this new result, the deduced electron-phonon coupling parameter $\ensuremath{\lambda}$ was increased from a range of 0.3--0.6 to 0.4--0.9, which now overlaps with the distribution of experimental values (0.7--1.2). Thus, the disagreements found in the literature about superconductivity-related properties in fullerides may be in part explained by the great sensitivity of those DFT results to the choice of functional.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.054 | 0.006 |
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".