Analysis of the multireference state-universal coupled-cluster <i>Ansatz</i>
Bibliographic record
Abstract
An algorithm for the multireference (MR) cluster analysis of configuration interaction (CI) wave functions, based on the state-universal (SU) coupled-cluster (CC) Ansatz of Jeziorski and Monkhorst, is formulated. It is illustrated on two often-studied model systems that consist of two (the so-called H4 model) and four (the H8 model), slightly stretched, hydrogen molecules and enable one to vary the degree of quasidegeneracy via a single geometric parameter. The role played by higher-than-two-body clusters is examined and their importance in the MR effective Hamiltonian formalism, particularly in the presence of intruder states, is explored in detail. It is pointed out that in contrast with the single-reference CC methods, the MR SU CC approach with singles and doubles (CCSD) cannot yield exact energies even when exact one- and two-body clusters are available. It is shown that this limitation, which is particularly crucial in the presence of intruder states, can be remedied by employing a small subset of higher-than-pair-cluster amplitudes, extracted via cluster analysis from the MR CISD wave functions that are based on the same model space as the SU CCSD method, not unlike in the reduced MR CCSD method.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".