Metastable high-pressure single-bonded phases of nitrogen predicted via genetic algorithm
Bibliographic record
Abstract
The recently proposed genetic algorithm for crystal structure prediction combined with first-principles structural optimizations is used to investigate the high-pressure structures of solid nitrogen. Starting from a population of randomly generated eight-atom structures at $80\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, the evolutionary process not only recovers the four lowest-energy nonmolecular structures (CG, $C2∕c$, black phosphorus, and $Cmcm$ chain) predicted theoretically or known experimentally, but also reveals a metastable single-bonded three-dimensional structure. The stability of this structure at $80\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ is established by phonon calculations. At this pressure, the enthalpy of the structure is $0.17\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$/atom higher than that of the cubic gauche phase. The energetic difference between this structure and other nonmolecular high-pressure phases is explained from analysis of the local structural motifs.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".