Dynamics of Atomic Structure
Fluctuation of atomic structures of metal microclusters can be observed by using an electron microscope of atomic resolution with a television camera. Such a structural fluctuation is one of the characteristics of microclusters. By utilizing a computer, dynamical properties of small microclusters are studied for the size N = 13 bound by the Lennard-Jones interaction. The coexistence of solid-like and liquid-like phases is pointed out at the effective temperature between those for melting and freezing. On the other hand, for the transition-metal cluster of size N = 6, a fluctuating state that does not involve atomic diffusion has been found just below the melting temperature, and a transition to permutation isomers which accompany atomic diffusion just above the melting temperature. Thermal properties of transition-metal microclusters are studied by using Monte-Carlo simulations for the two cases: absence and presence of a magnetic interaction. A sharp magnetic transition exists even in the small magnetic cluster of size N = 7. Finally, rapid spontaneous alloying of microclusters recently observed is discussed.
KeywordsCopper Deposition Gold Cluster Fluctuate State Caloric Curve Pentagonal Symmetry
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