  Background: Exotic non-spherical nuclear pasta shapes are expected in nuclear
matter at just below saturation density because of competition between short
range nuclear attraction and long range Coulomb repulsion. Purpose: We explore
the impact of nuclear pasta on nucleosynthesis, during neutron star mergers, as
cold dense nuclear matter is ejected and decompressed. Methods: We perform
classical molecular dynamics simulations with 51200 and 409600 nucleons, that
are run on GPUs. We expand our simulation region to decompress systems from an
initial density of 0.080 fm^{-3} down to 0.00125 fm^{-3}. We study proton
fractions of Y_P=0.05, 0.10, 0.20, 0.30, and 0.40 at T =0.5, 0.75, and 1.0 MeV.
We calculate the composition of the resulting systems using a cluster
algorithm. Results: We find final compositions that are in good agreement with
nuclear statistical equilibrium models for temperatures of 0.75 and 1 MeV.
However, for proton fractions greater than Y_P=0.2 at a temperature of T = 0.5
MeV, the MD simulations produce non-equilibrium results with large rod-like
nuclei. Conclusions: Our MD model is valid at higher densities than simple
nuclear statistical equilibrium models and may help determine the initial
temperatures and proton fractions of matter ejected in mergers.
