  Mixtures of light elements with heavy elements are important in inertial
confinement fusion and planetary science. We explore the physics of molecular
scale mixing through a validation study of equation of state (EOS) properties.
Density functional theory molecular dynamics (DFT-MD) at elevated-temperature
and pressure is used to obtain the thermodynamic state properties of pure
xenon, ethane, and various compressed mixture compositions along their
principal Hugoniots. To validate these simulations, we have performed shock
compression experiments using the Sandia Z-Machine. A bond tracking analysis
correlates the sharp rise in the Hugoniot curve with the completion of
dissociation in ethane. The DFT-based simulation results compare well with the
experimental data along the principal Hugoniots and are used to provide insight
into the dissociation and temperature along the Hugoniots as a function of
mixture composition.
