Atomistic Modeling of Hydrogen Structure II Gas Hydrate Structural and Mechanical Properties
Bibliographic record
Abstract
Gas hydrates are crystalline inclusion compounds similar to ice, formed by trapping gas molecules within hydrogen-bonded water cages.Their unique host-guest interactions, stabilized by weak van der Waals forces which are significantly weaker than the hydrogen bonds between the water molecules of the cages, make them promising candidates for hydrogen storage.However, research on their properties and stability is limited due to the high costs of experiments and high computational power required for ab initio simulations.Ab initio methods without approximations can be used to accurately investigate the mechanical behavior of gas hydrates.This thesis aims to explore the storage capacity, mechanical properties, elastic anisotropies, and stability limits of sII hydrogen hydrates to better characterize hydrate-based hydrogen storage technology and fill the gaps in the literature.The specific objectives include, examining the effects of hydrate structure, hydrogen concentration, and pressure on structural and mechanical stability, and computing crucial elastic constants and mechanical properties of sII hydrogen hydrates.The studies presented reveal that hydrogen occupancy in the small and large cages of the hydrate lattice significantly impacts structural stability, with maximum occupancies depending on the hydrogen bond breakage or being constrained by cage volume expansion.Detailed analysis of bulk moduli and the equation of state revealed a bi-continuous composite structure where small and large cages form continuous phases with nearly equal volume fractions.Furthermore, the mechanical properties and elastic anisotropies of sII hydrogen hydrates are investigated, considering various hydrogen compositions, revealing significant effects of hydrogen composition of the cages on the lattice anisotropy and hydrate's response to external forces, characterized by Young's modulus, shear modulus, bulk modulus, and Poisson's ratio.Finally, the stability limits of sII hydrates under triaxial strains are examined by detailed analyses of the bond parameters, indicating a decrease in
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 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".