Constant entropy sampling and release waves of shock compressions

We present several equilibrium methods that allow to compute isentropic processes, either during the compression or the release of the material. These methods are applied to compute the isentropic release of a shocked monoatomic liquid at high pressure and temperature. Moreover, equilibrium results of isentropic release are compared to the direct nonequilibrium simulation of the same process. We show that due to the viscosity of the liquid but also to nonequilibrium effects, the release of the system is not strictly isentropic

Exploring warm dense matter using quantum molecular dynamics

For dense plasmas produced in shock experiments, the influence of the media on the isolated atomic properties can no longer be treated as a perturbation and conventional atomic physics approaches usually fail. Recently, quantum molecular dynamics (QMD) has been used to successfully predict static, dynamical and optical properties in this regime within the framework of a first principle method. In this short report, we illustrate the usefulness of the method for dense plasmas with a few selected examples: the equation of state of liquid deuterium, the electrical properties of expanded metals, the optical properties of shocked insulators, and the interaction of femto-second lasers with gold thin films

Structural and dynamical properties of hot dense matter by a Thomas-Fermi-Dirac molecular dynamics

We use a model combining, in a consistent way, orbital-free density functional theory (OF-DFT) and molecular dynamics (MD), to compute the thermodynamical, structural and dynamical properties of Fe and Au plasmas at conditions relevant to astrophysics and inertial confinement fusion (ICF). The newly developed parallel numerical scheme presented here allows to propagate hundreds of particles and to obtain accurate transport properties. This allows us to investigate the validity of the commonly used one-component plasma (OCP) model in predicting the pair correlation, the diffusion and viscosity coefficients for these two high-temperature high-density plasmas

The viscosity of dense plasmas mixtures

We present estimations of the shear viscosity of a hydrogen-carbon mixture at various concentrations computed by molecular dynamics in the frame of Kubo currents obtained directly at the hydrodynamic limit through the Bernu-Vieillefosse formalism (Bernu B. and Vieillefosse P., Phys. Rev. A, 18 (1978) 2345). It is shown that, depending on the initial temperature of the mixture, a small amount of carbon in the hydrogen plasma can strongly reduce the viscosity (kinetic regime), but in some cases the mixing can lead to an increase (strong coupling). Those results are fitted and extended to an arbitrary mixture with the help of a one-fluid model

Average atom transport properties for pure and mixed species in the hot and warm dense matter regimes

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