Density Functional Study of Absorption and Resonance Raman Spectra of Pyromellitic Diahydride (PMDA) Anion
Bibliographic record
Abstract
The electronic structure of the low-energy states of pyromellitic diahydride (PMDA) anion is investigated in terms of density functional theory (DFT). The studies are carried out with a use of the local spin density VWN (Vosco−Wilk−Nusair) and the nonlocal spin density BP (Becke−Perdew) models. To explore the role of the diffuse functions located on carbon and oxygene atoms, the B3LYP method was also employed with 6-31+G* and 6-31G* basis sets. At this level of approximation, the Franck−Condon (FC) parameters were evaluated for the nine totally symmetric modes of PMDA anion in its low-energy dipole-allowed 1 2 B 3g and 1 2 B 1g states. These parameters are then employed to reconstruct and discuss the vibrational structure of the experimental absorption and RR spectra measured in the region corresponding to the low-energy 1 2 A u → 1 2 B 3g transition. It is shown that a weak mixing of the CC stretching modes upon excitation to the 1 2 B 3g state and an inhomogeneous broadening of vibronic transitions have a marked effect on the absorption and resonance Raman spectra.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".