Interlocking Triplet Electronic States of Isocyanic Acid: Sources of Nonadiabatic Photofragmentation Dynamics
Bibliographic record
Abstract
The triplet electronic states of isocyanic acid have been systematically investigated by means of state-of-the-art electronic structure methods, including various correlation techniques based on the coupled-cluster ansatz [CCSD, EOM-CCSD, CCSD(T), and BD(TQ)], second- through fifth-order Møller−Plesset perturbation theory (MP2-MP5), and the complete active space self-consistent field approach. The one-particle [(C,N,O)/H] basis sets for these studies ranged in quality from [4s2p1d/2s1p] to [7s6p5d4f3g2h1i/6s5p4d3f2g1h]. Vertical excitation energies were determined for the lowest 13 triplet states (5 valence, 8 Rydberg), and potential energy curves for bending to and from linearity were generated for 10 of these states, revealing intricate state interactions and numerous actual and avoided crossings. An extensive mapping was then executed for the interlocking ã 3 A ‘ ‘ and b̃ 3 A ‘ surfaces, which produced geometric structures, relative energies, harmonic vibrational frequencies, and selected large-amplitude vibrational eigenstates, for torsional conformers, inversion barriers, fragmentation barriers, dissociation products, and ionization limits, in addition to identifying intermingled conical intersections. The lowest-energy conformer on the ã 3 A ‘ ‘ surface is actually a skewed ( C 1 ) structure with a torsion angle of 143°, a barrier to planarity of only 74 cm -1, an adiabatic excitation energy near T 0 = 30 056 cm -1, and an exit barrier for 3 NH + CO fragmentation of only about = 3252 cm -1 . It is discovered that there are actually no legitimate minima (removed from conical intersections) on the b̃ 3 A ‘ surface, because in-plane optimizations bring associated structures below the companion 3 A ‘ ‘ state and subsequently connect them to the lowest triplet surface via torsional excursions along imaginary-frequency normal modes.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".