  The effect of ionic disorder on the principal Hugoniot is investigated using
Multiple Scattering Theory to very high pressure (Gbar). Calculations using
molecular dynamics to simulate ionic disorder, are compared to those with a
fixed crystal lattice, for both carbon and aluminum. For the range of
conditions considered here, we find that ionic disorder is most important at
the onset of shell ionization and that at higher pressures, the subtle effect
of the ionic environment is overwhelmed by the larger number of ionized
electrons with higher thermal energies.
