CaS2
CaS2 has a DFT band gap of 2.17 eV across 151 reported structures in 17 space groups. Cross-validated across 2 computational databases.
Key Properties
Cross-validated computational properties for CaS2, aggregated across 2 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 CaS2. Tight agreement means computed properties can be trusted without re-running calculations.
Only 1 independent DFT source (oqmd) reports a hull energy for CaS2, so cross-source agreement can't be assessed yet.
Reported Structures
Lowest-energy structures reported for CaS2, 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. |
|---|---|---|---|---|---|
| — | — | 2.17 | 0.0467 | -1.508 | — |
| — | — | 0.00 | 0.5706 | -0.985 | — |
| — | — | 0.00 | 1.0876 | -0.467 | — |
| — | — | 0.00 | 1.2696 | -0.286 | — |
| P1 (No. 1) | triclinic | — | — | — | 1.47 |
| P1 (No. 1) | triclinic | — | — | — | 2.53 |
| P1 (No. 1) | triclinic | — | — | — | 3.00 |
| P1 (No. 1) | triclinic | — | — | — | 2.41 |
| P1 (No. 1) | triclinic | — | — | — | 1.43 |
| P1 (No. 1) | triclinic | — | — | — | 1.73 |
| P1 (No. 1) | triclinic | — | — | — | 1.96 |
| P1 (No. 1) | triclinic | — | — | — | 1.37 |
Frequently Asked Questions
Common questions about CaS2, answered from cross-validated data.
What is the band gap of CaS2?
CaS2 has a DFT-computed band gap of 2.17 eV across 151 reported structures. Standard DFT underestimates band gaps, so the measured gap is typically larger.
Is CaS2 a metal, semiconductor, or insulator?
Is CaS2 thermodynamically stable?
How many polymorphs of CaS2 are known?
What elements does CaS2 contain?
Where does the data for CaS2 come from?
Data sources & attribution
- 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.
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