cQTP25: A new exchange–correlation functional for core-electron ionization energy
Bibliographic record
Abstract
We present a new exchange-correlation (XC) functional inspired by correlated orbital theory and designed to enhance the accuracy of core-electron ionization energy predictions as measured by x-ray photoelectron spectroscopy. This functional, referred to as cQTP25, differs from other Quantum Theory Project (QTP) functionals by optimizing the range-separation parameters through a targeted restriction of the orbital space to core 1s electrons only. We benchmarked cQTP25 against a diverse set of XC functionals spanning multiple rungs of Jacob's ladder in Density Functional Theory (DFT). The performance was evaluated primarily using the relation IP1s = -ɛ1s, but for completeness, we also computed core ionization potentials using the ΔDFT method. All calculations accounted for both non-relativistic and relativistic corrections. Overall, within Koopmans's framework, the QTP functionals perform best, and specifically cQTP25. The exception is the ΔDFT analysis, where M11, ωB97X, and BHandHLYP are more accurate and cQTP25 ranks fourth.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 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".