CO2
Carbon dioxide · Dry ice, Carbonic anhydride
Carbon dioxide is a stable, insulating molecular compound that plays a vital role in biological and industrial systems.
About Carbon dioxide
Carbon dioxide is a fundamental molecular compound consisting of carbon and oxygen. It is characterized by its wide-gap insulating electronic nature and high thermodynamic stability, placing it firmly on the convex hull of stable phases.
Due to its prevalence and stability, this compound is one of the most extensively studied materials in chemical databases. It serves as a critical component in atmospheric chemistry, biological respiration, and various industrial cooling and carbonation applications.
Key Properties
Cross-validated computational properties for Carbon dioxide, aggregated across 4 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.
Reported Structures
Lowest-energy structures reported for CO2, 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. |
|---|---|---|---|---|---|
| Pa-3 (No. 205) | cubic | 6.63 | 0.0000 | -8.144 | 1.76 |
| P42/mnm (No. 136) | tetragonal | 6.31 | 0.0054 | -8.139 | 1.74 |
| P42/mnm (No. 136) | tetragonal | 6.44 | 0.0069 | -8.137 | 1.68 |
| Cmce (No. 64) | orthorhombic | 6.59 | 0.0073 | -8.137 | 1.76 |
| R-3c (No. 167) | trigonal | 6.50 | 0.0074 | -8.137 | 1.74 |
| Pbcn (No. 60) | orthorhombic | 6.68 | 0.0105 | -8.134 | 1.70 |
| Pna21 (No. 33) | orthorhombic | 6.45 | 0.0155 | -8.129 | 1.70 |
| P41212 (No. 92) | tetragonal | 6.43 | 0.0168 | -8.128 | 1.57 |
| I41/a (No. 88) | tetragonal | 5.01 | 0.2975 | -7.847 | 1.73 |
| P21/c (No. 14) | monoclinic | 4.22 | 0.3186 | -7.826 | 1.94 |
| I-42d (No. 122) | tetragonal | 7.65 | 0.4496 | -7.695 | 3.11 |
| P212121 (No. 19) | orthorhombic | 6.75 | 0.5105 | -7.634 | 3.02 |
Applications
Where Carbon dioxide is used.
Frequently Asked Questions
Common questions about Carbon dioxide, answered from cross-validated data.
What is CO2?
Carbon dioxide is a stable, insulating molecular compound that plays a vital role in biological and industrial systems.
What is CO2 used for?
What is the band gap of CO2?
Is CO2 a metal, semiconductor, or insulator?
Is CO2 thermodynamically stable?
What is the crystal structure of CO2?
What is the density of CO2?
How many polymorphs of CO2 are known?
What elements does CO2 contain?
Where does the data for CO2 come from?
How It Compares
As a foundational molecular oxide, carbon dioxide serves as the benchmark for stability and electronic insulation within its chemical family, representing a highly robust and well-documented phase in structural materials science.
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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