HgCN2
HgCN2 is a semiconducting mercury-carbon-nitrogen compound that exists in a metastable state.
About HgCN2
HgCN2 is a semiconducting compound composed of mercury, carbon, and nitrogen. It represents a complex chemical system that has been documented across multiple structural databases, reflecting significant interest in its potential electronic properties.
As a material that sits above the thermodynamic hull, it is considered metastable. Its existence in various structural configurations highlights the intricate bonding behaviors possible within mercury-cyanide-related frameworks, making it a subject of study for those investigating unstable inorganic phases.
Key Properties
Cross-validated computational properties for HgCN2, 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 HgCN2. 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 HgCN2, 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. |
|---|---|---|---|---|---|
| Pbca (No. 61) | orthorhombic | 2.47 | 0.2784 | -19.115 | 5.96 |
| P21/c (No. 14) | monoclinic | 1.88 | 0.3046 | -19.089 | 6.01 |
| — | — | 2.40 | 0.3828 | 0.383 | — |
| — | — | 1.93 | 0.4051 | 0.405 | — |
| Pbca (No. 61) | orthorhombic | 2.49 | 0.5207 | 0.512 | — |
| P21/c (No. 14) | monoclinic | 1.99 | 0.5468 | 0.538 | — |
| P21/c (No. 14) | monoclinic | — | — | — | 6.55 |
| Pmm2 (No. 25) | orthorhombic | — | — | — | 6.36 |
| Pmm2 (No. 25) | orthorhombic | — | — | — | 5.52 |
| Pmm2 (No. 25) | orthorhombic | — | — | — | 5.91 |
Frequently Asked Questions
Common questions about HgCN2, answered from cross-validated data.
What is HgCN2?
HgCN2 is a semiconducting mercury-carbon-nitrogen compound that exists in a metastable state.
What is the band gap of HgCN2?
Is HgCN2 a metal, semiconductor, or insulator?
Is HgCN2 thermodynamically stable?
What is the crystal structure of HgCN2?
What is the density of HgCN2?
How many polymorphs of HgCN2 are known?
What elements does HgCN2 contain?
Where does the data for HgCN2 come from?
How It Compares
As a unique inorganic phase with no direct structural siblings currently classified alongside it, HgCN2 stands as a distinct, albeit metastable, entry in the landscape of mercury-based semiconductors.
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)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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