Chiral Molecules with Achiral Excited States: A Computational Study of 1,3-Dimethylallene
Bibliographic record
Abstract
Molecular orbital computations using the configuration interaction singles method and complete active space self-consistent field method were used to map out the electronic ground and excited states of 1,3-dimethylallene. Both open-shell and closed-shell singlet configurations were taken into account. Potential Energy Surfaces (PES) for the ground and the first two excited states were obtained over a two-mode grid composed of the C−C−C bending angle and the dihedral angle between the planes defined by the carbon atoms of the H 3 C−C=C and C=C−CH 3 groups. Several critical points located on the ground and first-excited PES were fully optimized by allowing all degrees of freedom to relax. The ground-state racemization reaction from the left-handed enantiomer to the right-handed was found to proceed via a barrier of 41 kcal/mol, in excellent agreement with the experimental value of 45.1 kcal/mol for the enthalpy of racemization. The ground-state transition-state geometry is shown to be planar-bent. The results indicate that 1,3-dimethylallene shows chiral structures in the ground state and achiral structures in the first-excited state. Coupled with the reported dipole-moment function, 1,3-dimethylallene is shown to be a useful molecule for coherently controlled racemic purification using our “laser distillation” scheme.
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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".