  Neutrinos in core collapse supernovae are likely trapped by neutrino-nucleus
elastic scattering. Using molecular dynamics simulations, we calculate neutrino
mean free paths and ion-ion correlation functions for heterogeneous plasmas.
Mean free paths are systematically shorter in plasmas containing a mixture of
ions compared to a plasma composed of a single ion species. This is because
neutrinos can scatter from concentration fluctuations. The dynamical response
function of a heterogeneous plasma is found to have an extra peak at low
energies describing the diffusion of concentration fluctuations. Our exact
molecular dynamics results for the static structure factor reduce to the Debye
Huckel approximation, but only in the limit of very low momentum transfers.
