Ab initio time-resolved X-ray spectroscopy: mechanistic insights into conical intersection dynamics
Bibliographic record
Abstract
Developments in ultrafast X-ray sources offer powerful new means of probing the complex nonadiabatic dynamics in photoexcited molecules. Of particular interest are the electronic and nuclear structures associated with conical intersections, which are predicted to have unique spectral signatures when probed using X-ray spectroscopies. Using high level ab initio quantum dynamics simulations and newly developed electronic structure techniques based on the DFT/MRCI formalism, we have simulated time-resolved X-ray spectroscopy (TRXAS and TRXPS) of a number of prototypical unsaturated organic chromophores. These spectroscopies are sensitive to all aspects of the ensuing dynamics and can distinguish between the different nuclear dynamical pathways that result in electronic relaxation. The ability of femtosecond X-ray spectroscopy to provide a clear picture of the wave packet dynamics near conical intersections is related to transient charge localization at specific atomic sites that is driven by the nuclear dynamics. These dramatic changes in the local charge environment are then 'reported' using the core-electrons localized on, or proximate to, the atoms involved in the formation of these transient electronic structures. Given the complexity of the measured signals, and the difficulty in empirically (and uniquely) mapping transient spectra to molecular structures, the role of accurate simulations will be essential for the interpretation of these new time-resolved spectroscopies.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".