An ab initio study of silicon dioxide in the warm dense matter regime

Silicon dioxide is a key geophysical material but it is also a widely used reference material in shock experiments. During giant impacts and in high-power laser experiments, SiO₂ is exposed to very high pressures and temperatures up to several times 10⁵ K. In both cases, SiO₂ is first compressed along the Hugoniot curve and then experiences an isentropic release. In shock-experiments, it can also undergo a reshock towards even higher compression states. As a reference material it needs to be characterized under all of these conditions with a high accuracy.

In this presentation we will show results from quantum molecular dynamics simulations applied to SiO₂ up to 30 g/cm³ and 5x10⁵ K. From these simulations, we extracted the equation of state of SiO₂ in this regime and compared it with several experiments ensuring its accuracy and its ability to serve as a reference EOS for impedance matching methods. We also explored structural and transport properties to be used in geophysical and hydrodynamic models.