Theoretical Insights into the Hydrated (10.4) Calcite Surface: Structure, Energetics, and Bonding Relationships
Bibliographic record
Abstract
Roothaan-Hartree-Fock molecular orbital methods were applied to investigate the ground-state structural, energetic properties, and bonding relationships of the hydrated (10.4) calcite surface. The adsorption of water molecules was modeled at the 6-31G(d,p) level of theory using Ca(n)(CO(3))(n) slab cluster models (4 <or= n <or= 18) with a varying number of H(2)O monomers (2 <or= (H(2)O)(n) <or= 6) interacting with the surface. Modeling results add fresh insights into the detailed 3D structural registry of the first and second hydration layers and the reconstructed (10.4) calcite surface, complementary to the information acquired from earlier atomistic, density functional, X-ray scattering, and grazing incidence X-ray diffraction studies. Both the modeled energies and geometries agree best with results of earlier density functional calculations, supporting the associative character of adsorbed water molecules. Two adsorption configurations are postulated: (i) H(2)O molecules interacting with surface Ca through ionic bonding and by hydrogen bonding to a surface O with their dipole slightly oblique above the surface (1st hydration layer), and (ii) H(2)O molecules that hydrogen bond to surface O and to H(2)O molecules in the first hydration layer with their dipole nearly parallel to the surface (2nd hydration layer). These interactions are consistent with the "chemisorption" and "physisorption" of H(2)O on calcite surfaces, proposed on the basis of previous thermogravimetric and Fourier-transformed infrared studies. Most significant is the distortion of the surface Ca-O octahedra caused by the relaxation (and possibly rupture) of some Ca-O bonds upon hydration, weakening the topmost atomic layer. These findings are consistent with interpretations of X-ray photoelectron spectroscopy, density functional theory, and electrokinetic studies that suggest the preferential release of surface Ca atoms over surface CO(3) groups upon hydration of the cleavage surface. These insights will help to elucidate mechanisms of carbonate mineral dissolution, the rearrangement of surface layers, ion replacement, charge development, and solute transport through subsurface lattice layers.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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 | 0.000 |
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".