Singlet-triplet excitation energies of R1R2Si=Si silylene derivatives: A G4/W1BD theoretical study
Bibliographic record
Abstract
Well-to-well (WWE~S-T~) and adiabatic (AE~S-T~) singlet-triplet excitation energies were calculated at the Gaussian-4 (G4) and W1BD levels of theory for a suite of mono- and disubstituted R~1~R~2~Si=Si silylene derivatives (where R~1~/R~2~=H, CH~3~, NH~2~, OH, and F), as well as H~2~C=Si and HN=Si. Reasonable agreement was obtained with prior E~S-T~ estimates at the CCSD(T)/6-311++G(d,p)//QCISD/6-31G(d) and B3LYP/AUG-cc-pVTZ//B3LYP/6-31+G(d) levels of theory. The G4/W1BD E~S-T~ are systematically higher than these prior estimates by between 1 to 5 kcal/mol, averaging positive deviations of about 1-2 and 3-4 kcal/mol from the CCSD(T) and B3LYP estimates, respectively. Qualitative ground state multiplicity agreement between the four levels of theory was found for H~2~C=Si, H~2~Si=Si, HN=Si, (H~3~C)HSi=Si, (H~3~C)~2~Si=Si, (H~2~N)HSi=Si, (H~2~N)~2~Si=Si, (HO)~2~Si=Si, and F~2~Si=Si. However, there is disagreement as to the ground state multiplicity for (HO)HSi=Si and FHSi=Si using the different theoretical methods. For (HO)HSi=Si, G4 and W1BD methods predict either a slightly energetically favored ground state singlet (G4) or an energetic degeneracy between the two multiplicities (W1BD). For FHSi=Si, both the G4 and W1BD methods predict a clear ground state singlet, whereas the CCSD(T)/6-311++G(d,p)//QCISD/6-31G(d) method predicts effective energetic degeneracy, and the B3LYP/AUG-cc-pVTZ//B3LYP/6-31+G(d) method predicts a clear ground state triplet. In light of the current high-level calculations, the ground state multiplicities of (HO)HSi=Si and FHSi=Si should be considered uncertain due to disagreement among various levels of theory. Resolution of the actual ground state multiplicities of these compounds will likely need to await experimental data.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.002 |
| 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".