  For the study of crystal formation and dynamics we introduce a simple
two-dimensional monatomic model system with a parametrized interaction
potential. We find in molecular dynamics simulations that a surprising variety
of crystals, a decagonal and a dodecagonal quasicrystal are self-assembled. In
the case of the quasicrystals the particles reorder by phason flips at elevated
temperatures. During annealing the entropically stabilized decagonal
quasicrystal undergoes a reversible phase transition at 65% of the melting
temperature into an approximant, which is monitored by the rotation of the de
Bruijn surface in hyperspace.
