The dynamics of Si nano-clusters during epitaxial growth has been investigated with molecular dynamics simulation using the Tersoff potential. Several nm sized Si cluster formed during rapid cooling was found to deform instantaneously upon impingement on a Si(100) substrate at the same time with the spontaneous ordering of the atomic structure to that of the substrate. Due to the increased fraction of high-energy atoms at the surface, smaller clusters (similar to 1 nm) are favorable for such a deformation even at lower temperatures. This is the advantage of loosely-bound cluster as growth precursor to attain epitaxy with reduced impact energies. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.