Quantum Simulation Study and Development of Dissociative Equations of State for Planetary Materials

In this study, we present thermal chemical calculations and first-principles density functional theory (DFT) simulations on key materials relevant to planetary science, including SiO₂ and H₂O. Our objective is to investigate and characterize the nature of chemical dissociation across a broad range of densities and temperatures, thereby facilitating the development of dissociative equations of state (EOS). Chemical dissociation can significantly influence the heat capacity of liquids and is a critical factor that should be incorporated into EOS development for various compounds. Notably, dissociative EOS can differ substantially from traditional non-dissociative EOS, which have been the standard in the field. In this poster, we present the thermodynamic properties of these compounds, alongside density- and temperature-dependent distributions of dissociated species, computed using DFT simulations and LLNL's Cheetah thermochemistry code. In addition, we aim to explore the EOSs on mixtures of these compounds, enhancing our understanding of planetary materials under extreme conditions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.