Relaxation of excitons in ionic halides: a molecular dynamics study<sup>†</sup>
Bibliographic record
Abstract
We report here the results of molecular dynamics simulation of hole and exciton relaxation in KBr and NaBr. The semi-classical program previously used for study of static properties has been modified to implement the solutions of Newton's equations with a time step of 0.50 femtosecond. The hole self-trapping process is studied at 80 K. A rapid bond-length oscillation is observed which damps out very fast in NaBr (in about 0.5 picosecond). The relaxation of a Frenkel-type exciton (localized on a single site) is studied at 10 K. It is found that the localization of the excited electron at an anion site drives the relaxation process, resulting in the simultaneous formation of H and F centres. In KBr, the F-H pair created has the F and H about 14 Å apart (third neighbours). In NaBr, the separation is about 4 Å. The maximum relaxation is achieved in about 1.5 ps in KBr, and in about 0.75 ps in NaBr. These results are discussed in comparison with recent femtosecond spectroscopic work.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".