<i>Ab</i><i>initio</i>modelling of intermetallics with CuAl<sub>2</sub>structure type: computed powder patterns from cell-and-type CRYSTMET entries
Bibliographic record
Abstract
Searchable calculated powder patterns of crystalline substances are commonly used nowadays to complement experimental patterns for the identification of materials by diffraction methods. Reliable such patterns are often calculable from the known cell, type and chemistry data on types with fixed Wyckoff positions, like NaCl, but not on typeC16 ofAB2compounds, with CuAl2as its representative material, because of the variablexcoordinate of itsBsite.Ab initiocell and coordinate relaxation for four key compounds withC16 type, all started from the samec/a= 1 andx= 1/6 configuration, converged on the correct axial ratios and fractional coordinates. A linear regression on a plot ofxcoordinates optimizedab initioat experimental cell dataversusX-ray coordinates for all 48C16-type compositions for pure-phase compounds with coordinates in the CRYSTMET database gavey= 0.998x,R2= 0.88. Credible calculated powder patterns were then produced for AlHf2, AlZr2, AuTl2, BCr2, GaHf2, IrZr2and TlTh2, all with cell, type and pure-phase composition information but no coordinates in this database, using their X-ray cell data andab initiocoordinates. Those patterns, now inserted in the search system of the database, will help users identify those phases from powder diffraction angle and intensity data. The corresponding entries in a new `X-ray cell-and-type,ab initiocoordinates' category of full structure entries may be helpful for other applications, such as the simulation of EXAFS spectra or of backscattered electron patterns.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".