Solvation Structure, Thermodynamics, and Molecular Conformational Equilibria for <i>n</i>-Butane in Water Analyzed by Reference Interaction Site Model Theory Using an All-Atom Solute Model
Bibliographic record
Abstract
For the four thermodynamic states: temperature T = 283.15, 298.15, 313.15, and 328.15 K and the corresponding bulk water density ρ = 0.9997, 0.9970, 0.9922, and 0.9875 g cm -3, for which experimental data are available, we have studied hydration structure, hydration thermodynamics, and molecular conformational equilibria for n -butane in water at infinite dilution, by means of the hypernetted chain closure reference interaction site model (HNC−RISM) theory with an all-atom solute model. The hydration structures of the trans and the gauche conformers of n -butane are presented and analyzed at the atomic level in terms of the atomic solute−solvent radial distribution functions. With these radial distribution functions as input, the n -butane conformational average hydration free energies, energies, enthalpies, and entropies are calculated. At room temperature, the normalized equilibrium distribution of n -butane conformers, the water solvent-induced rotational free energy surface and the trans − gauche and trans − cis cavity thermodynamic properties are calculated. With the optimized nonbonded potential parameters based on the CHARMM96 all-atom model for alkanes (Yin, D.; Mackerell, A. D., Jr. J. Comput. Chem. 1998, 19, 334), n -butane hydration thermodynamics and its conformational equilibria in water are well described by the HNC−RISM theory in comparison with the available experimental and computer simulation results. We also calculated the solute density derivatives of the water−water radial distribution functions δ h vv, with the optimized CHARMM96 all-atom model, the united-atom OPLS (optimized potentials for liquid simulations), and the all-atom OPLS models for n -butane, respectively. The δ h vv ( r ) reflect the effect of increased pressure disrupting the hydrogen bonding between water molecules. The all-atom model seems to enhance such an effect due to the well-documented shortcoming of the RISM theory in the treatment of the excluded volume of so-called auxiliary sites.
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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) | 0.000 | 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) | 0.000 | 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".