An assessment of theoretical methods for the study of transition metal carbonyl complexes: [Cl2Rh(CO)2]− and [Cl2Rh(CO)]− as case studies
Bibliographic record
Abstract
A comparative theoretical study of the equilibrium geometries, vibrational frequencies, and reaction energetics of Rh–CO bond activation in the [Cl2Rh(CO)2]− and [Cl2Rh(CO)]− complexes has been performed using the B3LYP density functional method and the traditional correlated second-order Møller–Plesset (MP2), quadratic configuration interaction with single and double substitutions (QCISD) and coupled-cluster single double (triple) [CCSD(T)] methods. CCSD(T) is employed herein as a benchmark method to examine the validity of the B3LYP and MP2 methods in studies of transition metal complexes. The results show that the geometries and energies obtained with the B3LYP method agree quite well with the QCISD and CCSD(T) results. The conventional MP2 method yields poor results for all geometries, vibrational frequencies, and reaction energies. It is noteworthy that the relative reaction energies calculated at the highest correlated CCSD(T) level using the B3LYP and MP2 geometries are comparable even though the B3LYP and MP2 geometries differ significantly from each other. The absolute energies calculated with the QCISD and CCSD(T) methods at the B3LYP geometries are all lower than those obtained with the MP2 geometries, indicating that the B3LYP method could be more reliable for the study of the geometries and energetics of the catalytic reactions. Basis set effects have been examined by B3LYP calculations. The present results provide a comprehensive assessment of the widely used ab initio theoretical methods for the study of transition metal carbonyl complexes.
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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 | 0.003 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".