<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 type C 16 of AB 2 compounds, with CuAl 2 as its representative material, because of the variable x coordinate of its B site. Ab initio cell and coordinate relaxation for four key compounds with C 16 type, all started from the same c / a = 1 and x = 1/6 configuration, converged on the correct axial ratios and fractional coordinates. A linear regression on a plot of x coordinates optimized ab initio at experimental cell data versus X-ray coordinates for all 48 C 16-type compositions for pure-phase compounds with coordinates in the CRYSTMET database gave y = 0.998 x , R 2 = 0.88. Credible calculated powder patterns were then produced for AlHf 2 , AlZr 2 , AuTl 2 , BCr 2 , GaHf 2 , IrZr 2 and TlTh 2 , all with cell, type and pure-phase composition information but no coordinates in this database, using their X-ray cell data and ab initio coordinates. 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 initio coordinates' 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 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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".