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Hydrogen-Helium Mixtures in the Interiors of Giant Planets
J. Vorberger, I. Tamblyn, B. Militzer, S.A. Bonev Physical Review B, 75, 024206 (2007) Using first-principles density functional molecular dynamics simulations, this work examines hydrogen-helium mixtures under conditions representative of the deep interiors of giant planets, spanning densities from 0.19 to 0.66 g/cm3 and temperatures between 500 K and 8000 K. The study reveals that helium substantially alters the structure of liquid hydrogen by shortening and strengthening hydrogen molecular bonds, creating more stable molecules compared to pure hydrogen under identical conditions. The authors also evaluate the accuracy of the commonly used linear mixing approximation and discover deviations of up to 8% in energy and volume from linear mixing at constant pressure in the region of molecular dissociation, revealing notable limitations of this simplified model in certain thermodynamic regimes. |
