Comparison of various Franck–Condon and vibronic coupling approaches for simulating electronic spectra: The case of the lowest photoelectron band of ethylene
Bibliographic record
Abstract
Various time independent approaches for simulating electronic absorption spectra are discussed and applied to the lowest band (10.2-11.4 eV) of the photoelectron spectrum of ethylene. The electronic structure calculations for the ionized states of ethylene are performed using the Equation of Motion Coupled Cluster method for Ionization Potentials (IP-EOM-CCSD) in a TZ2P basis set. Various Franck-Condon (FC) and vibronic coupling model Hamiltonian approaches are used to simulate the spectrum and a comparison is made to the experimental data. The potential energy surface is highly anharmonic and it is necessary to use more sophisticated FC approaches than the traditional harmonic approach to obtain a qualitatively correct simulation of the spectrum. Duschinsky rotation is found to play an important role in determining the detailed intensity pattern of the spectrum, while non-adiabatic effects are found not to be important. The spectrum is found to be very sensitive to the precise values of some of the parameters used in the vibronic model, that determine the details of the adiabatic potential energy surface.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| 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".