An accurate determination of rovibrational spectra using the externally corrected coupled-cluster approaches: LiH ground state
Bibliographic record
Abstract
Recently acquired highly precise spectroscopic data for the ground state of LiH and its various isotopomers are employed to carry out a critical assessment of the performance of the externally corrected coupled-cluster (CC) approaches. Both the amplitude and energy-corrected approaches are considered, in particular the reduced multireference CC method with singles and doubles (RMR CCSD) and the asymmetric energy formula based CCSD-[MR] method, both exploiting the same modest-size multireference configuration interaction (MR CISD) wave function, based on an M-dimensional reference space, as the source of higher than pair clusters. To assess the size of the basis set errors relative to those of the methods employed, the comparison is also made with the full CI (FCI) results at the cc-pVTZ level. The rovibrational energy levels and the corresponding transition frequencies are then computed for various isotopomers of LiH using the theoretically determined potentials at the cc-pVXZ (X=D, T, Q, and 5) and the extrapolated completebasis-set-limit levels and a comparison is made with the experiment as well as with the existing theoretical results, particularly those exploiting the CC approaches. The role of adiabatic corrections is also assessed. It is shown that both the RMR CCSD and CCSD-[4R] methods, yielding an almost indistinguishable results, are capable of accounting for the nondynamical correlation effects that are lacking in the standard single-reference CCSD approaches.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".