CI
Carbon monoiodide is an unstable, wide-gap insulating binary compound composed of carbon and iodine.
About CI
Carbon monoiodide is a binary compound consisting of carbon and iodine. Due to its position above the thermodynamic hull, it is considered a highly unstable species that is difficult to isolate or maintain under standard conditions.
Despite its instability, the compound is a subject of significant interest in computational materials science. It serves as a model for understanding carbon-halogen bonding dynamics and the limits of structural stability in simple covalent systems.
Key Properties
Cross-validated computational properties for CI, 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 CI. 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 CI, 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/n (No. 86) | tetragonal | 3.42 | 0.7606 | -4.617 | 2.58 |
| — | — | 3.34 | 0.8681 | 0.864 | — |
| P1 (No. 1) | triclinic | 2.32 | 1.0257 | 1.024 | — |
| — | — | 0.00 | 2.4169 | 2.413 | — |
| — | — | 0.00 | 2.4169 | 2.413 | — |
| — | — | 0.00 | 2.5981 | 2.594 | — |
| — | — | 0.00 | 2.6575 | 2.654 | — |
| — | — | 0.00 | 3.0018 | 2.998 | — |
| — | — | 0.00 | 3.0134 | 3.010 | — |
| P1 (No. 1) | triclinic | — | — | — | 4.34 |
| P1 (No. 1) | triclinic | — | — | — | 7.97 |
| P1 (No. 1) | triclinic | — | — | — | 3.78 |
Frequently Asked Questions
Common questions about CI, answered from cross-validated data.
What is CI?
Carbon monoiodide is an unstable, wide-gap insulating binary compound composed of carbon and iodine.
What is the band gap of CI?
Is CI a metal, semiconductor, or insulator?
Is CI thermodynamically stable?
What is the crystal structure of CI?
What is the density of CI?
How many polymorphs of CI are known?
What elements does CI contain?
Where does the data for CI come from?
How It Compares
As a binary carbon-iodide species, this compound represents a fundamental, albeit transient, building block in the study of halogenated carbon materials. Its role is primarily theoretical, providing insight into the electronic behavior of wide-gap insulators in systems where thermodynamic stability is elusive.
Data sources & attribution
- 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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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