Molecular Dynamics Study of the Adsorption Behavior of Normal Alkanes on a Relaxed α-Al<sub>2</sub>O<sub>3</sub> (0001) Surface
Bibliographic record
Abstract
Adsorption behavior of two normal alkanes (C 11 and C 200 ) with explicit hydrogens on a relaxed α-Al 2 O 3 (0001) surface at 150 °C was studied using classical molecular dynamics (MD) simulation along with the use of the COMPASS force field. Prior to the MD simulations, first principle density functional theory (DFT) calculations were carried out to relax the alumina (0001) surface that was created by cleaving the corresponding crystal structure. It was found that orientation of the adsorbed segments and the number of carbons adsorbed seem to be insensitive to the chain length. The computed adsorption energy per mole of adsorbed CH 2 agrees well with those obtained from inverse gas chromatography measurements. Also, both simulation and experimental results showed that the adsorption energy decreased with increasing chain length. It was observed that molecular planes containing the skeletal carbons of the alkane segments that formed the first adsorption layer tend to orient parallel to the alumina surface, regardless of chain length. However, there existed a small amount of C 11 segments adopting the perpendicular orientation. For both C 11 and C 200, the average distance between the neighboring adsorbed segments was determined to be 4.6 Å which is slightly lower than the distance between two adjacent normal alkane molecules in their crystalline form but is equal to the inter-atomic distance between the aluminum atoms in the surface layer of the alumina surface. The present work suggests that both the orientation and adsorption energy of normal alkanes on the alumina (0001) surface depends on whether the surface is relaxed or not.
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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 | 0.000 | 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) | 0.001 | 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".