Interacting chain model for poly(ethylene glycol) from first principles—stretching of a single molecule using the transfer matrix approach
Bibliographic record
Abstract
Based on ab initio quantum-mechanical calculations on short segments (up to four subunits) of poly(ethylene glycol), we construct n-state interacting chain models with n=3 or 7 with nearest-neighbor interactions that also account fully for the geometrical structure of the molecule (bond lengths, bond angles, and dihedral angles). For chains up to N=21 subunits we construct, in the three-state model, all 3N conformers exactly. For longer chains we apply the transfer matrix method in the Gibbs ensemble in the presence of an external force. The force-extension curve is calculated with high accuracy by both methods, and the results are compared with each other and with experimental data. We show that the infinite chain length limit is reached at about N=200. We analyze the effect of variation of geometrical and energy parameters in the model, as well as the effect of chain length on our final results. Chain end distribution functions, probabilities of rotational states and the persistence length are calculated. We show that additional rotational states beyond those of the potential minima used in the rotational-isomeric-state approximation must be included for an accurate description.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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 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".