Potential energy barriers for dissociative attachment to HF.HF and HCl.HCl: Ab initio study
Bibliographic record
Abstract
Abstract Dissociative attachment (DA) of an electron to the dimers of HF and HCl, reaction (1) equation image has been investigated by theoretical calculations at MP2 and CCSD(T) levels with large basis sets. Transition structures (TSs) for the loss of an H atom and formation of the FHF − and ClHCl − anions were located by analytic methods. Initial electron attachment to HF.HF dimer occurs without activation and yields a dipole‐bound anion state (DBS) as shown previously. Reaction (1) is endothermic by 65.8 kJ/mol at the CCSD(T)/aug‐cc‐pVDZ level. An intermediate ion‐induced dipole complex between H · and FHF − is reached from the DBS over a potential barrier of 66.6 kJ/mol. Analysis of the charge distribution as a function of the distance to the departing H · reveals that the diffuse DBS collapses to a much more compact valence configuration prior to the TS being reached. In the valence configuration, the electron occupies the σ* orbital of the terminal HF bond. DA to HCl.HCl differs from the fluorine case in several important respects. HCl.HCl does not form a DBS. Rather, electron attachment occurs by direct insertion into the σ* orbital of the terminal HCl bond with an activation energy of 20.3 kJ/mol. As in the fluorine case, electron capture occurs before the TS. The electron density collapses to a valence configuration when the HCl bond is stretched to about 1.45 Å, intermediate between that in the neutral dimer, 1.28 Å, and in the TS to DA, 1.57 Å. A “T‐shaped” ion‐induced dipole complex, bound by about 2 kJ/mol, lies between the TS and the separated H atom and ClHCl − anion products. With respect to DA, the chlorine system is intermediate between the fluorine system and the previously reported bromine system. The latter was found to undergo DA with a 0.0‐kJ/mol barrier. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
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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".