Invited Speakers

Evan Reed reed23@llnl.gov Lawrence Livermore Natl Lab

Computational dynamics at extreme conditions Shock wave compression enables the study of high temperature (>1 eV), high pressure (> 1 Mbar), and dynamic properties of materials. These properties are of astrophysical, geological and other significance. Shock waves can be generated routinely in a laboratory setting but the short timescales of such experiments (as short as 1 ns or less) make experimental diagnostics of the shocked material properties very challenging. The development of theoretical and computational techniques for modeling shock processes on these timescales are therefore of significant value in guiding and interpreting shock experiments. I will present recent theoretical and computational predictions of novel and unexpected electromagnetic phenomena that occur when shock waves propagate through crystalline materials including photonic crystals and ionic crystals such as NaCl. These phenomena include reversed and anomalously large Doppler effects that occur when light reflects from the shock front, and the emission of temporally coherent (narrow bandwidth) radiation in the 1-100 THz frequency regime. Finally, I will present a multi-scale molecular dynamics simulation technique that enables the calculation of the dynamical evolution of atomistic scale properties of steady shock waves for timescales orders of magnitude longer than previously possible. This technique has been utilized with density-functional theory and tight-binding molecular dynamics to study phase transformations in shocked graphite and chemical reactions in shocked nitromethane.