Oxygen<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>-edge XANES of germanates investigated using first-principles calculations
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Bibliographic record
Abstract
O $K$-edge x-ray absorption near-edge structure (XANES) spectra of $\ensuremath{\alpha}$-quartz-type and rutile-type $\mathrm{Ge}{\mathrm{O}}_{2}$ polymorphs and of ${\mathrm{K}}_{2}{\mathrm{Ge}}_{8}{\mathrm{O}}_{17}$ have been analyzed using first-principles plane-wave pseudopotential calculations. XANES spectra have been calculated using supercell including core-hole effects and good agreement with experiment has been obtained. In the the case of $\mathrm{Ge}{\mathrm{O}}_{2}$ polymorphs, local density of empty states has been performed and peaks in the experimental spectra can be assigned to transitions involving hybridization of the $\mathrm{O}\phantom{\rule{0.2em}{0ex}}p$ orbitals with the $\mathrm{Ge}\phantom{\rule{0.2em}{0ex}}s$, $\mathrm{Ge}\phantom{\rule{0.2em}{0ex}}p$, $\mathrm{Ge}\phantom{\rule{0.2em}{0ex}}sp$, and $\mathrm{Ge}\phantom{\rule{0.2em}{0ex}}d$ orbitals. Furthermore, peak positions in the theoretical spectra appear to be correlated with changes in the Ge-O-Ge angle as well as indirectly with the Ge coordination geometry. Analysis of O $K$-edge XANES spectra for individual O sites in ${\mathrm{K}}_{2}{\mathrm{Ge}}_{8}{\mathrm{O}}_{17}$ shows that oxygens shared between two fivefold Ge atoms or one fourfold and one fivefold Ge atom exhibit subtle shifts to lower energy of the peaks, which have been previously observed in alkali germanate glasses at and above the germanate anomaly.
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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 | 0.000 |
| 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) | 0.000 | 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 it