Evaluation of Shear-Slip Transitions in Crystalline Aspirin by Density-Functional Theory
Why this work is in the frame
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Bibliographic record
Abstract
Crystalline aspirin has been shown to form two distinct polytypes, or polymorphs, that differ only in one unit-cell dimension. The second polytype is metastable and has been proposed to convert to the original form through a one-dimensional shear-slip mechanism. The feasibility of the {100}<001> shear-slip system, relating the two known aspirin forms, is examined computationally by the use of periodic-boundary density-functional theory (B86bPBE-XDM). A low barrier of ca. 10 kJ/mol per molecule is computed, which is estimated to be consistent with the observed interconversion rate, accounting for uncertainties in the treatment of thermal effects. The barrier is shown to increase under applied pressure, explaining previous experimental observations that compression of aspirin-II did not result in reversion to aspirin-I under the time scales considered. Finally, the advisability of using aspirin, or other compounds that form similar polytypes, as tests of computational methods for studies of polymorphism is discussed. Because of their high geometric similarity, both polytypes are predicted to be effectively degenerate regardless of the treatment of intermolecular dispersion.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.003 | 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 it