HI
Hydrogen iodide · Hydriodic acid
Hydrogen iodide is a colorless gas that dissolves readily in water to form a strong mineral acid. It is primarily utilized as a chemical reagent in organic synthesis and as a precursor for the production of various iodine-containing compounds.
HI
Overview
Key Properties
Cross-validated computational properties for Hydrogen iodide, aggregated across 5 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.
4.07 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.
0.004 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.
Near hull (likely stable)
4 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
191
5 databases, 24 space groups
Crystallography
Reported Structures
Lowest-energy structures reported for HI, 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. |
|---|---|---|---|---|---|
| C2/c (No. 15) | monoclinic | 4.07 | 0.0044 | -2.635 | 3.42 |
| P3m1 (No. 156) | Trigonal | — | — | — | 2.16 |
| Cm (No. 8) | Monoclinic | — | — | — | 7.77 |
| C2/c (No. 15) | — | — | — | — | — |
| Pnma (No. 62) | Orthorhombic | — | — | — | 5.41 |
| Cm (No. 8) | Monoclinic | — | — | — | 5.31 |
| Cm (No. 8) | Monoclinic | — | — | — | 5.01 |
| Pnma (No. 62) | Orthorhombic | — | — | — | 8.62 |
| Pbcm (No. 57) | Orthorhombic | — | — | — | 6.33 |
| Pnma (No. 62) | Orthorhombic | — | — | — | 5.35 |
| Cmcm (No. 63) | Orthorhombic | — | — | — | 8.42 |
| P21/m (No. 11) | Monoclinic | — | — | — | 5.53 |
Uses
Applications
Where Hydrogen iodide is used.
Organic synthesisChemical manufacturingPharmaceutical productionAnalytical chemistry
Reference
Frequently Asked Questions
Common questions about Hydrogen iodide, answered from cross-validated data.
What is HI?
Hydrogen iodide is a colorless gas that dissolves readily in water to form a strong mineral acid. It is primarily utilized as a chemical reagent in organic synthesis and as a precursor for the production of various iodine-containing compounds.
More questions
What is HI used for?
Hydrogen iodide (HI) is used in organic synthesis, chemical manufacturing, pharmaceutical production, and analytical chemistry.
What is the band gap of HI?
Hydrogen iodide (HI) has a DFT-computed band gap of 4.07 eV across 191 reported structures.
Is HI a metal, semiconductor, or insulator?
With a wide band gap up to 4.07 eV it is an insulator / wide-band-gap material.
Is HI thermodynamically stable?
Hydrogen iodide (HI) has a lowest energy above hull of 0.004 eV/atom (near hull (likely stable)).
What is the crystal structure of HI?
The lowest-energy reported polymorph of Hydrogen iodide (HI) is monoclinic symmetry, space group C2/c (No. 15).
What is the density of HI?
The computed density of the ground-state structure of Hydrogen iodide (HI) is 3.42 g/cm³.
How many polymorphs of HI are known?
191 structures of HI are reported across 5 databases, spanning 24 distinct space groups.
What elements does HI contain?
Hydrogen iodide (HI) contains H and I (2 elements).
Where does the data for HI come from?
HI data is cross-referenced from materials_project, mpaloe, jarvis, nomad.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
- nomad — Data from NOMAD. Cite: Draxl & Scheffler, J. Phys. Mater. 2, 036001 (2019).
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