Superconducting and dynamically stable polymorphs of elemental calcium predicted under high pressure
Bibliographic record
Abstract
Abstract Compressed calcium undergoes successive structural transitions under high pressure. In this study, high-pressure polymorphs of elemental calcium were investigated using a machine-learned interatomic potential combined with a sensible random structure search. Two new energetically favourable and dynamically stable phases were predicted, crystallizing in the P -42 1 c and P -31 c space groups at high pressure. Both structures are predicted to be metallic and likely exhibit phonon-mediated superconductivity. Using the Allen-Dynes modified McMillan equation, the superconducting critical temperatures ( T c ) were estimated to be 26 K for the P -42 1 c phase at 200 GPa and 31 K for the P -31 c phase at 250 GPa, which are comparable to the highest experimentally observed T c for calcium (29 K at 216 GPa). These relatively high T c values are attributed to strong electron–phonon coupling between partially occupied d states and moderate-frequency phonon modes. These findings provide further insight into the complex polymorphism and superconductivity of elemental calcium under extreme conditions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 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 teacher head, 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".