Surface electronic structures of Ba overlayers on W(100), W(110), and W(111)
Bibliographic record
Abstract
The total energy distributions (TEDs) in field emission (FE) and photofield emission (PFE) and the work functions have been measured at room temperature for Ba adsorbed on W(100), W(110), and W(111) in the range of coverage from 0 to 1 ML (monolayer). We observe two initial state peaks and three final state peaks on $\mathrm{W}(100)∕\mathrm{Ba}$, six initial state peaks and one final state peak on $\mathrm{W}(110)∕\mathrm{Ba}$, and two initial state peaks and two final state peaks on $\mathrm{W}(111)∕\mathrm{Ba}$. We extend the full-potential linear augmented plane wave method for the electronic structures of periodic lattices to calculate the emission current in FE and surface PFE at a metal-adsorbate-vacuum interface. Our calculations account for the energies of all of the initial state features observed experimentally in FE and surface PFE from clean W(100), in PFE and angle-resolved inverse photoemission spectroscopy from $\mathrm{W}(100)∕\mathrm{Ba}$ at 1 ML, and for all of the peaks observed in FE, surface PFE, and photoemission from $\mathrm{W}(110)∕\mathrm{Ba}$ at 0.6 ML and from $\mathrm{W}(111)∕\mathrm{Ba}$ at 1 ML. The $d{z}^{2}$-like surface states of the Swanson hump [L. W. Swanson and L. C. Crouser, Phys. Rev. Lett. 16, 389 (1966)] of clean W(100) hybridize with $s$-like states of the $c(2\ifmmode\times\else\texttimes\fi{}2)$ overlayer and are shifted by $\ensuremath{-}1.60\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ to yield a prominent peak in PFE. An isolated Ba $c(2\ifmmode\times\else\texttimes\fi{}2)$ layer is found to be weakly metallic; the metallicity is greatly enhanced when it is adsorbed on a W(100) substrate. The TEDs in PFE from the atomically less dense overlayer $\mathrm{W}(110)∕\mathrm{Ba}$ $(2\ifmmode\times\else\texttimes\fi{}2)$ are dominated by substrate-overlayer interactions, while those from the atomically denser overlayer $\mathrm{W}(111)∕\mathrm{Ba}$ $(1\ifmmode\times\else\texttimes\fi{}1)$ are dominated by interactions within the overlayer. Our results yield evidence that above $1∕3$ ML Ba coverage on W(111), which corresponds to a commensurate $({3}^{1∕2}\ifmmode\times\else\texttimes\fi{}{3}^{1∕2})R30\ifmmode^\circ\else\textdegree\fi{}$ overlayer, the interstitial sites fill in randomly to form a commensurate $(1\ifmmode\times\else\texttimes\fi{}1)$ overlayer at 1 ML coverage.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".