Molecular dynamic (MD) simulations offer a powerful means of understanding
the microscopic characteristics of shock-propagation through solids and fluids,
especially for the short spatial and temporal scales relevant to laser-driven shocks.
First-principles molecular dynamics can be directly compared with time-resolved
experimental measurements, and methods based on empirical (embedded-atom)
potentials fitted to first-principles quantum-mechanical calculations are effective
for MD simulations of shock propagation through many millions of atoms. In comparison, thermodynamic approaches based on free-energy considerations
do not provide detailed information about mechanical-relaxation or phase- transformation processes within the shock front. We illustrate these ideas by way of embedded-atom simulations of shock-wave propagation through copper crystals of different orientation.