Fig. 3: Ab initio calculations of hydration heat and optimized structure of δ-K0.33MnO2 ∙ nH2O. | Nature Communications

Fig. 3: Ab initio calculations of hydration heat and optimized structure of δ-K0.33MnO2 ∙ nH2O.

From: Excellently balanced water-intercalation-type heat-storage oxide

Fig. 3: Ab initio calculations of hydration heat and optimized structure of δ-K0.33MnO2 ∙ nH2O.The alternative text for this image may have been generated using AI.

a Heat of hydration (enthalpy benefit due to the water intercalation) obtained by ab initio calculation for δ-K0.33MnO2 ⋅ nH2O, b the optimized structure with H2O molecules for each content of water. c A typical coordination of K+ ions and H2O molecules sited in an interlayer for n = 0.5, where the averaged distances of K-O(H2O) and K-H are 2.83 Å and 2.97 Å, respectively. The internal energy of H2O gas (=3nRT) is considered by assuming that H2O is an ideal gas with degree of freedom 3 (translational) + 3 (rotation). The two sets, free relaxed (red) and fixed lattice constants (blue), are calculated.

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