CaH2: enthalpy of formation

10 accepted literature formation-enthalpy value(s) (experimental 5, DFT 5).

Systems: Ca–H

Literature values

Enthalpy of formation of CaH2 reported in the literature (10)
Value	Phase as printed	T (K)	Class	Method	System	Source	Location
-208 kJ/mol (basis unstated)	CaH2	1093	experimental	Obtained in the similar way by Treadwell	Ca–H	[1] Wang 2011 cites Johnson 1939 doi	Table 1, p. 3, row 3 report
-188 kJ/mol (basis unstated)	CaH2	1093	experimental	Partial pressures of H2 over a mixture of Ca and CaH2 at temperatures from 1053 K to 1133 K	Ca–H	[1] Wang 2011 cites Treadwell 1953	Table 1, p. 3, row 2 report
-184 kJ/mol (basis unstated)	CaH2	298.15	experimental	Experimental	Ca–H	[1] Wang 2011 cites Mueller 1968	Table 1, p. 3, row 5 report
-183.6 kJ/mol (basis unstated)	CaH2	298.15	experimental	Experimental	Ca–H	[1] Wang 2011 cites Lide 2002	Table 1, p. 3, row 6 report
-170.2 kJ/mol (basis unstated)	CaH2	298.15	experimental	Experimental	Ca–H	[1] Wang 2011 cites Mueller 1968	Table 1, p. 3, row 5 report
-172.1 kJ/mol (basis unstated)	CaH2	0	DFT	Ab initio, DFT, VASP, PAW-GGA	Ca–H	[1] Wang 2011 cites Wolverton 2007 doi	Table 1, p. 3, row 4 report
-172 kJ/mol (basis unstated)	CaH2	0	DFT	Ab initio, DFT, VASP, PAW-GGA	Ca–H	[1] Wang 2011 cites Wolverton 2004 doi	Table 1, p. 3, row 7 report
-167.3 kJ/mol (basis unstated)	CaH2	0	DFT	Ab initio, DFT, CASTEP, NCPP-GGA	Ca–H	[1] Wang 2011	Table 1, p. 3, row 1 report
-162.9 kJ/mol (basis unstated)	CaH2	0	DFT	Ab initio, DFT, CASTEP, NCPP-GGA	Ca–H	[1] Wang 2011	Table 1, p. 3, row 1 report
-161.1 kJ/mol (basis unstated)	CaH2	0	DFT	Ab initio, DFT, VASP, PAW-GGA	Ca–H	[1] Wang 2011 cites Wolverton 2007 doi	Table 1, p. 3, row 4 report

Uncertainty budget

Components kept separate, in the value's unit (literature SCHEMA.md, UNCERTAINTY_CALIBRATION.md): effective = max(sqrt(max(printed, reading, method)^2 + composition^2 + conversion^2), scatter). The method floor is the robust between-study scatter of the method class in ORCHID (calibrated) or a documented prior; printed values and printed uncertainties are unchanged.

Uncertainty budget of the literature values of CaH2
Value	Unit	Reading	Method (class, basis)	Effective
-208	kJ/mol (basis unstated)	0.05	12.3 (experimental_unspecified, cleaned_below_threshold)	12.3
-188	kJ/mol (basis unstated)	0.05	12.3 (experimental_unspecified, cleaned_below_threshold)	12.3
-184	kJ/mol (basis unstated)	0.05	12.3 (experimental_unspecified, cleaned_below_threshold)	12.3
-183.6	kJ/mol (basis unstated)	0.05	12.3 (experimental_unspecified, cleaned_below_threshold)	12.3
-170.2	kJ/mol (basis unstated)	0.05	12.3 (experimental_unspecified, cleaned_below_threshold)	12.3
-172.1	kJ/mol (basis unstated)	0.05	29.9 (dft, calibrated)	29.9
-172	kJ/mol (basis unstated)	0.05	29.9 (dft, calibrated)	29.9
-167.3	kJ/mol (basis unstated)	0.05	29.9 (dft, calibrated)	29.9
-162.9	kJ/mol (basis unstated)	0.05	29.9 (dft, calibrated)	29.9
-161.1	kJ/mol (basis unstated)	0.05	29.9 (dft, calibrated)	29.9

Sources

Kun Wang, Junlin Du, Xiangcheng Kong, Xiaoqin Zeng, Jianxin Zou, Zhilin Li et al., Ab initio and thermodynamic investigation on the Ca–H system, International Journal of Hydrogen Energy 36, 13632-13639 (2011). doi:10.1016/j.ijhydene.2011.08.018

Please cite

R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735569
R. Arróyave, J. Saal, D. Shin, ORCHID-Parity: DFT-vs-experiment formation-enthalpy benchmark (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735943
R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23736065

Also cite the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); G. Kim, S. V. Meschel, P. Nash, W. Chen, Experimental formation enthalpies for intermetallic phases and other inorganic compounds, Scientific Data 4 (2017) 170162, https://doi.org/10.1038/sdata.2017.162; B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file. Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

@misc{orchid_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_dft_benchmark_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Parity: DFT-vs-experiment formation-enthalpy benchmark}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735943},
  url       = {https://doi.org/10.5281/zenodo.23735943},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}