Singlet-triplet excitation energies of R~1~R~2~Si=Si silylene derivatives: A G4/W1BD theoretical study
Bibliographic record
Abstract
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 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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".