HF
Hydrogen fluoride · Hydrofluoric acid
Hydrogen fluoride is a stable, insulating binary compound widely utilized as a versatile chemical reagent and industrial etchant.
About Hydrogen fluoride
Hydrogen fluoride is a thermodynamically stable compound consisting of hydrogen and fluorine. Its electronic character as a wide-gap insulator defines its reactivity and makes it a critical reagent in various chemical processes. Given its extensive documentation across multiple structural databases, it remains one of the most thoroughly characterized small-molecule systems in inorganic chemistry.
The compound is highly valued for its ability to act as a precursor for fluorine-containing chemicals and as a specialized etchant. Its inherent stability and unique bonding characteristics allow it to facilitate complex transformations that are difficult to achieve with other mineral acids, cementing its importance in modern manufacturing and laboratory research.
Key Properties
Cross-validated computational properties for Hydrogen fluoride, 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.
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.
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.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of HF. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for HF, 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. |
|---|---|---|---|---|---|
| — | — | 8.64 | 0.0000 | -1.719 | — |
| Cm (No. 8) | monoclinic | 8.22 | 0.0000 | -1.520 | — |
| Cmcm (No. 63) | orthorhombic | 8.10 | 0.0000 | -4.378 | 1.95 |
| Cmcm (No. 63) | orthorhombic | 7.35 | 0.0279 | -1.492 | — |
| Cmc21 (No. 36) | orthorhombic | 6.74 | 0.0306 | -4.347 | 1.72 |
| — | — | 7.82 | 0.0951 | -1.624 | — |
| — | — | 8.97 | 0.1318 | -1.588 | — |
| — | — | 8.38 | 0.1509 | -1.569 | — |
| — | — | 7.17 | 0.1793 | -1.540 | — |
| P-6m2 (No. 187) | hexagonal | 6.49 | 0.3654 | -1.154 | — |
| — | — | 6.35 | 0.6770 | -1.042 | — |
| P4mm (No. 99) | tetragonal | 6.12 | 0.7094 | -0.810 | — |
Applications
Where Hydrogen fluoride is used.
Frequently Asked Questions
Common questions about Hydrogen fluoride, answered from cross-validated data.
What is HF?
Hydrogen fluoride is a stable, insulating binary compound widely utilized as a versatile chemical reagent and industrial etchant.
What is HF used for?
What is the band gap of HF?
Is HF a metal, semiconductor, or insulator?
Is HF thermodynamically stable?
What is the crystal structure of HF?
What is the density of HF?
How many polymorphs of HF are known?
What elements does HF contain?
Where does the data for HF come from?
How It Compares
As a foundational inorganic compound, hydrogen fluoride serves as a primary reference point for the study of simple binary fluorides. It occupies a unique position in chemical synthesis due to its distinct combination of high stability and aggressive reactivity, setting the standard for handling and application protocols within the broader class of hydrogen halides.
Data sources & attribution
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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