H2O
water · dihydrogen monoxide, oxidane
Water is a polar inorganic compound that is essential for all known forms of life. It acts as a universal solvent and plays a critical role in biological processes, climate regulation, and various industrial applications.
HO
Overview
Key Properties
Cross-validated computational properties for water, 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.
0.05–5.78 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)
3 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
445
5 databases, 44 space groups
Validation
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of H2O. 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.
1.00 / 1.00
Trust tier: high
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
0.000 eV
EAH spread across sources
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
3
jarvis, materials_project, nomad
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
All match
Crystallography
Reported Structures
Lowest-energy structures reported for H2O, 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. |
|---|---|---|---|---|---|
| Cmc21 (No. 36) | orthorhombic | 5.52 | 0.0000 | -5.193 | 1.04 |
| Cc (No. 9) | monoclinic | 5.59 | 0.0004 | -5.192 | 1.04 |
| P63cm (No. 185) | hexagonal | 5.53 | 0.0011 | -5.192 | 1.04 |
| R-3 (No. 148) | trigonal | 5.44 | 0.0056 | -5.187 | 1.32 |
| P41212 (No. 92) | tetragonal | 5.49 | 0.0067 | -5.186 | 1.28 |
| P212121 (No. 19) | orthorhombic | 5.78 | 0.0111 | -5.182 | 1.43 |
| P21 (No. 4) | monoclinic | 5.46 | 0.0120 | -5.181 | 1.43 |
| P212121 (No. 19) | orthorhombic | 5.67 | 0.0124 | -5.180 | 1.43 |
| I41/amd (No. 141) | tetragonal | 5.29 | 0.0205 | -5.172 | 1.64 |
| P42nm (No. 102) | tetragonal | 5.28 | 0.0252 | -5.168 | 1.65 |
| C2221 (No. 20) | orthorhombic | 5.36 | 0.0494 | -5.143 | 1.18 |
| C2221 (No. 20) | orthorhombic | 5.33 | 0.0680 | -5.125 | 1.22 |
Synthesis
Synthesis Routes
Literature-extracted synthesis procedures targeting H2O.
Sol-Gel
Procedure available · ceder_solid_state
Sol-Gel
Procedure available · ceder_solid_state
Sol-Gel
Procedure available · ceder_solid_state
Sol-Gel
Procedure available · ceder_solid_state
Sol-Gel
Procedure available · ceder_solid_state
Sol-Gel
Procedure available · ceder_solid_state
Uses
Applications
Where water is used.
drinking waterindustrial solventcoolant in power generationchemical synthesisagriculture
Reference
Frequently Asked Questions
Common questions about water, answered from cross-validated data.
What is H2O?
Water is a polar inorganic compound that is essential for all known forms of life. It acts as a universal solvent and plays a critical role in biological processes, climate regulation, and various industrial applications.
More questions
What is H2O used for?
water (H2O) is used in drinking water, industrial solvent, coolant in power generation, chemical synthesis, and agriculture.
What is the band gap of H2O?
water (H2O) has a DFT-computed band gap of 0.05–5.78 eV across 445 reported structures.
Is H2O a metal, semiconductor, or insulator?
With a wide band gap up to 5.78 eV it is an insulator / wide-band-gap material.
Is H2O thermodynamically stable?
Yes — water (H2O) sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of H2O?
The lowest-energy reported polymorph of water (H2O) is orthorhombic symmetry, space group Cmc21 (No. 36).
What is the density of H2O?
The computed density of the ground-state structure of water (H2O) is 1.04 g/cm³.
How many polymorphs of H2O are known?
445 structures of H2O are reported across 5 databases, spanning 44 distinct space groups.
How is H2O synthesized?
Literature-reported routes for H2O include sol-gel (10 procedures documented).
What elements does H2O contain?
water (H2O) contains H and O (2 elements).
Where does the data for H2O come from?
H2O data is cross-referenced from materials_project, jarvis, mpaloe.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
- mpaloe — Data from mpaloe.
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