Conformational Behavior of Chemisorbed Azobenzene Derivatives in External Electric Fields: A Theoretical Study
Bibliographic record
Abstract
Azobenzene derivatives have been shown to act as molecular switches when exposed to an applied electric field or tunneling electrons. Many applications require the switching molecule to be adsorbed on a surface. However, stable conformations and the isomerization energetics of adsorbed azobenzenes can be very different from the analogous more thoroughly studied behaviors in the gas phase or liquid solution. In this study, we investigate the zero-density limit behavior of cis and trans N -(2-mercaptoethyl)-4-phenylazobenzamide chemisorbed on a Au(111) surface. For all calculations, we employ the Perdew−Burke−Erzenhof functional as implemented in the SIESTA package, with a double-ζ plus polarization basis set. A large number of starting geometries were equilibrated, and several stable configurations were identified for both the trans- and cis-adsorbed isomers. The most stable are those in which the azobenzene moiety is parallel to the surface. Applied external electric fields in the usual STM range of ±1−3 V/nm produce minimal changes in these geometries. We find that the strength of the dispersive interactions between the extended conjugated system and the metallic surface is such that switching between parallel and upright geometries of single-molecules is unlikely to occur because of coupling to such a field. Although the presence of the surface slightly modifies the ground electronic state pathways for isomerization, this process is also not accessible through simple field−molecule coupling effects.
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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 | 0.001 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".