  The mobility of polymer chains in perfect polyethylene (PE) crystal was
calculated as a function of temperature and chain length through Molecular
dynamics (MD) in united atom approximation. The results demonstrate that the
chain mobility drastically increases in the vicinity of the phase transition
from the orthorhombic to quasi-hexagonal phase. In the quasi-hexagonal phase,
the chain mobility is almost independent on temperature and inversely
proportional to the chain length.
