Thermodynamic Data from Unpublished Sources to Support the New Reference Equation of State for Carbon Dioxide

During work on a new equation of state for carbon dioxide [E.W. Lemmon, A.H. Harvey, and R. Hellmann, Alternative Fundamental Equation of State for Fluid Carbon Dioxide, NIST Internal Report 8608 (2026), https://doi.org/10.6028/NIST.IR.8608], we obtained unpublished data from several sources. These represent numerical values for data only presented graphically in a publication, or in some cases data not present in the publication at all.
With the permission of the authors, we document and deposit these data here so they will be available for future workers. These include data for the melting curve at high pressures, the isochoric heat capacity (including near the critical point and in the two-phase region), the sound speed and density at high pressures, and the vapor pressure of the liquid. It also includes values of the second, third, and fourth virial coefficients calculated by R. Hellmann from state-of-the-art pair and three-body potentials.
For ease of electronic processing, the data elements are formatted as comma-separated values (.csv).
More details about the file contents are in the README.txt file and in the headings of individual files.
The literature papers connected with these data are as follows:
-- E.H. Abramson, "Three-Phase Melting Curves in the Binary System of Carbon Dioxide and Water," J. Phys.: Conf. Ser. 950, 042019 (2017), https://doi.org/10.1088/1742-6596/950/4/042019
-- P.C. Albright, T.J. Edwards, Z.Y. Chen, and J.V. Sengers, "A scaled fundamental equation for the thermodynamic properties of carbon dioxide in the critical region," J. Chem. Phys. 87, 1717 (1987), https://doi.org/10.1063/1.453238
-- F. Datchi et al., "Structure of liquid carbon dioxide at pressures up to 10 GPa," Phys. Rev. B 94, 014201 (2016), https://doi.org/10.1103/PhysRevB.94.014201
-- V.M. Giordano, F. Datchi, and A. Dewaele, "Melting curve and fluid equation of state of carbon dioxide at high pressure and high temperature," J. Chem. Phys. 125, 054504 (2006), https://doi.org/10.1063/1.2215609
-- R. Hellmann, "Ab initio potential energy surface for the carbon dioxide molecule pair and thermophysical properties of dilute carbon dioxide gas," Chem. Phys. Lett. 613, 133-138 (2014), https://doi.org/10.1016/j.cplett.2014.08.057
-- R. Hellmann, "Nonadditive three-body potential and third to eighth virial coefficients of carbon dioxide," J. Chem. Phys. 146, 054302 (2017), https://doi.org/10.1063/1.4974995
-- A. Kartal Dogan, G. Bonnier, A. Uytun, I Kocas, and Y. Durgut, "Toward Carbon Dioxide Vapor-Pressure Thermometer," Int. J. Thermophys. 32, 2230 (2011), https://doi.org/10.1007/s10765-011-1091-y
-- J.W. Magee and J.F. Ely, "Specific Heats (Cv) of Saturated and Compressed Liquid and Vapor Carbon Dioxide," Int. J. Thermophys. 7, 1163 (1986), https://doi.org/10.1007/BF00503973