Structure and Dynamics of β-Cyclodextrin in Aqueous Solution at the Density-Functional Tight Binding Level
Bibliographic record
Abstract
Structure and dynamics of beta-cyclodextrin (beta-CyD), a prototype host for inclusion compounds of biological interest, is investigated by means of density-functional based tight-binding molecular dynamics (MD) simulations. The computational protocol is benchmarked against available experimental data and first-principles calculations. Solvent-solute interactions, including the diffusion into and dwell time of the solvent in the cavity of beta-CyD, are studied with a hybrid QM/MM method. Comparison of MD simulations of beta-CyD in the gas phase and in water shows that the solvent reduces the flexibility of the structure framework, while the terminal hydroxyl groups become more flexible and are embedded in a network of hydrogen bonds. Our 160 ps MD simulations, provide enough sampling to discuss the dynamics of the water inside the cavity. The dwell time of the encapsulated water molecule has a wide distribution with a peak at 70 fs. Surprisingly, despite only the 17% difference between the "top" and "bottom" opening area of the beta-CyD cone, 64% of the water molecules enter the cavity through the slightly bigger "bottom" aperture.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| 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".