Molecular-dynamics modeling of the Hugoniot of shocked liquid deuterium

Abstract

Using our previously developed hydrogen tight-binding model, we performed equilibrium molecular-dynamics simulations to obtain the internal energy and pressure of the deuterium fluid at $39$ separate (density, temperature) points. Our simulations are thought to represent the energetics of fluid hydrogen accurately, including molecular dissociation. We fit the thermodynamically-consistent simulation data with a virial expansion, obtaining a high-quality equation of state (EOS) fit. The fitting data span the ranges 0.58 $<{\rho }_D<$ 1.47 g/cm${}^3$ and 3000 $<T<\mathrm{}$ 31 250 K, and the deduced EOS is thought to have a similar range of reliability. Our Hugoniot for shocked liquid deuterium shows a sharp rise in pressure and temperature at around $0.65$–$0.70$ g/cm${}^3$. We compare our theoretical Hugoniot to recent experimental and theoretical results.