Fig. 4: Thermodynamics of NaCl·RH2O mixture at 1600 K and 100 GPa. | Nature Communications

Fig. 4: Thermodynamics of NaCl·RH2O mixture at 1600 K and 100 GPa.

From: Stability of high-temperature salty ice suggests electrolyte permeability in water-rich exoplanet icy mantles

Fig. 4

a Gibbs free energy of mixing \(\Delta {g}_{{mix}}\) as computed from a fixed pressure approach and a complete sampling of the reduced configuration space (blue circles). In this case the configuration entropy is exact. Black (with correction for the GGA volume overestimation in B2 NaCl) and red (without) lines correspond to \(\Delta {g}_{{mix}}\) calculated from the fixed volume approach (see text and Supplementary Information) and a random sampling of the entire configuration space. Due to the limited sampling, the configuration entropy is less constrained in this approach. Inset: \(\Delta {g}_{{mix}}\) at 200 GPa and 1600 K. b Relative volume (blue) and density (red) differences between \({{{{{\rm{NaCl}}}}}}\cdot R{{{{{{\rm{H}}}}}}}_{2}{{{{{\rm{O}}}}}}\) and \({{{{{{\rm{H}}}}}}}_{2}{{{{{\rm{O}}}}}}\). Crosses corresponds to individual configurations and pluses to Boltzmann averages obtained from the complete sampling of the reduced configuration space. Lines correspond to the model derived from the fixed volume approach.

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