H8Mg4
H8Mg4 has a DFT band gap of 1.95–3.71 eV across 14 reported structures in 7 space groups; its lowest-energy polymorph is tetragonal (P42/mnm (No. 136)). Cross-validated across 3 computational databases.
At a glance
Key Properties
Cross-validated computational properties for H8Mg4, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
1.95–3.71 eV
Range across DFT structures
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
0.000 eV/atom
Best (lowest) across sources
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
On hull (stable)
2 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
14
3 databases, 7 space groups
Crystallography
Reported Structures
Lowest-energy structures reported for H8Mg4, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| P42/mnm (No. 136) | tetragonal | 3.71 | 0.0000 | -3.090 | 1.46 |
| Pbcn (No. 60) | orthorhombic | 3.63 | 0.0019 | -3.088 | 1.48 |
| Pa-3 (No. 205) | cubic | 3.00 | 0.0353 | -3.054 | 1.59 |
| Pca21 (No. 29) | orthorhombic | 2.35 | 0.0438 | -3.046 | 1.63 |
| Pbca (No. 61) | orthorhombic | 2.07 | 0.0459 | -3.044 | 1.63 |
| Pnma (No. 62) | orthorhombic | 1.95 | 0.0817 | -3.008 | 1.77 |
| Fm-3m (No. 225) | cubic | 0.00 | 0.1094 | -2.980 | 1.62 |
| Pbcn (No. 60) | — | — | — | — | — |
| Pbcn (No. 60) | — | — | — | — | — |
| Pca21 (No. 29) | — | — | — | — | — |
| Pa-3 (No. 205) | — | — | — | — | — |
| — | — | — | — | — | 0.98 |
Reference
Frequently Asked Questions
Common questions about H8Mg4, answered from cross-validated data.
What is the band gap of H8Mg4?
H8Mg4 has a DFT-computed band gap of 1.95–3.71 eV across 14 reported structures.
More questions
Is H8Mg4 a metal, semiconductor, or insulator?
With a wide band gap up to 3.71 eV it is an insulator / wide-band-gap material.
Is H8Mg4 thermodynamically stable?
Yes — H8Mg4 sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of H8Mg4?
The lowest-energy reported polymorph of H8Mg4 is tetragonal symmetry, space group P42/mnm (No. 136).
What is the density of H8Mg4?
The computed density of the ground-state structure of H8Mg4 is 1.46 g/cm³.
How many polymorphs of H8Mg4 are known?
14 structures of H8Mg4 are reported across 3 databases, spanning 7 distinct space groups.
What elements does H8Mg4 contain?
H8Mg4 contains H and Mg (2 elements).
Where does the data for H8Mg4 come from?
H8Mg4 data is cross-referenced from materials_project, aflow, omat24.
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Related Compounds
Other Hydrogen Storage Hydrides in the database.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- aflow — Data from AFLOW. Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012).
- omat24 — Data from OMat24 (Meta FAIR). Cite: Barroso-Luque et al., arXiv 2410.12771 (2024).
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