PHONONS AND STRUCTURE IN NANO-CLUSTERS - A MOLECULAR-DYNAMICS STUDY FOR AL

The generalized phonon density of states for Al nano-clusters has been studied theoretically using molecular dynamics. In this way anharmoni c effects could be fully considered. In order to investigate the struc ture of the clusters, we have also calculated the structure factor S(q ) (Fourier transform of the pair correlation function). The calculatio ns were done for systems consisting of 500 atoms and for several tempe ratures. Stable and metastable cluster states are observed: The cluste rs in the metastable stare show a well defined peak in the structure f actor S(q) which we interpret as superstructure. The appearance of the superstructure in the metastable state is accompanied by substantial changes in the phonon density of states. (C) 1997 Acta Metallurgica In c.