  The structural, dynamic, and vibrational properties during the heat transfer
process in Si/Ge superlattices, are studied by analyzing the trajectories
generated by the ab initio Car-Parrinello molecular dynamics simulation. The
radial distribution functions and mean square displacements are calculated and
further discussions are made to explain and probe the structural changes
relating to the heat transfer phenomenon. Furthermore, the vibrational density
of states of the two layers (Si/Ge) are computed and plotted to analyze the
contributions of phonons with different frequencies to the heat conduction.
Coherent heat conduction of the low frequency phonons is found and their
contributions to facilitate heat transfer are confirmed. The Car-Parrinello
molecular dynamics simulation outputs in the work show reasonable
thermophysical results of the thermal energy transport process and shed light
on the potential applications of treating the heat transfer in the
superlattices of semiconductor materials from a quantum mechanical molecular
dynamics simulation perspective.
