Materials at Extreme Conditions [Slides]
The area of warm, dense matter (WDM) has received considerable attention recently due its identification with an assortment of environments as diverse as the interiors of exoplanets, the atmospheres of stars, inertial confinement fusion capsules, and the plasma from laser interactions with materials from clusters to nanostructures that span temperatures from a few thousand (~ 1 eV) to a few million (~ 100 eV) degrees Kelvin and densities from a few hundredths solid (~ 10 21 atoms/cm 3 ) to hundreds of times compressed solid (~ 10 26 atoms/cm 3 ). The WDM regime, which resembles a transient "soup" of atoms, molecules, ions, and free electrons, presents a particularly difficult challenge although one being met by high-energy-density physics (HEDP) experiments, involving high-powered lasers and pulse-power devices, as well as through the development of sophisticated theoretical and computation physics techniques. While the nuclei conform to a classical treatment within molecular dynamics simulations, the electrons require a quantum mechanical treatment of a large collection of atoms, periodically replicated in space. The electronic structure calculations, which closely resemble those of atomic and molecular physics for large molecules or clusters, generally utilize Density Functional Theory (DFT) approaches. From these simulations, we extract various properties such as equation-of-state, transport coefficients, and opacities, which characterize the particular regime. We discuss various theoretical procedures and examine several representative environments from planetary interiors to hot, dense plasmas.