NO
Nitric oxide · Nitrogen monoxide
Nitric oxide is a reactive, semiconducting diatomic molecule that functions as a crucial signaling agent in biological systems and a key intermediate in atmospheric chemistry.
About Nitric oxide
Nitric oxide is a simple diatomic molecule consisting of nitrogen and oxygen. As a semiconducting species, it plays a vital role in various chemical and biological processes, acting as a fundamental signaling agent in mammalian physiology. Its electronic configuration makes it highly reactive and central to atmospheric chemistry.
Despite its significance, this compound is considered thermodynamically unstable relative to its constituent elements. It has been extensively characterized across multiple structural databases, reflecting its importance in both fundamental research and industrial applications.
Key Properties
Cross-validated computational properties for Nitric oxide, 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.
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 NO. 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 NO, 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. |
|---|---|---|---|---|---|
| P-1 (No. 2) | triclinic | 0.00 | 0.3754 | 0.234 | — |
| C2/c (No. 15) | monoclinic | 0.00 | 0.4128 | 0.271 | — |
| P212121 (No. 19) | orthorhombic | 0.00 | 0.5446 | -6.613 | 1.61 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.5452 | -6.612 | 1.47 |
| P212121 (No. 19) | orthorhombic | 0.00 | 0.5530 | -6.604 | 1.55 |
| P212121 (No. 19) | orthorhombic | 0.00 | 0.6217 | -6.536 | 2.66 |
| C2/c (No. 15) | monoclinic | 0.17 | 0.9663 | -6.191 | 1.43 |
| C2/c (No. 15) | monoclinic | 0.00 | 0.9715 | 0.830 | — |
| — | — | 0.00 | 2.5840 | 2.204 | — |
| — | — | 0.00 | 2.6289 | 2.249 | — |
| — | — | 0.00 | 2.6992 | 2.319 | — |
| — | — | 0.00 | 2.6993 | 2.319 | — |
Applications
Where Nitric oxide is used.
Frequently Asked Questions
Common questions about Nitric oxide, answered from cross-validated data.
What is NO?
Nitric oxide is a reactive, semiconducting diatomic molecule that functions as a crucial signaling agent in biological systems and a key intermediate in atmospheric chemistry.
What is NO used for?
What is the band gap of NO?
Is NO a metal, semiconductor, or insulator?
Is NO thermodynamically stable?
What is the crystal structure of NO?
What is the density of NO?
How many polymorphs of NO are known?
What elements does NO contain?
Where does the data for NO come from?
How It Compares
As a unique diatomic nitrogen oxide, this compound serves as a critical reference point for understanding the bonding and reactivity of nitrogen-oxygen systems, standing as one of the most essential and widely studied small molecules in the chemical sciences.
Data sources & attribution
- 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)
- 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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
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