Thermal Stability of Micro-Clusters
Anharmonic vibrations of atoms in a micro-cluster are theoretically studied by using the self-consistent phonon formalism. Atoms are assumed to interact on each other through a pairwise interatomic potential. The free energy of a cluster is minimized by using a model reference system in which a central atom is vibrating with a frequency ω0 and the surrounding atoms with ω1. We investigate the thermal softening of atomic vibrations, the thermal expansion and the vibrational instability for different micro-clusters. As for N=13 clusters, Cuboctahedron becomes instable at lower temperature than Icosahedron. The thermal stability of micro-clusters is discussed in terms of the instability temperature.
KeywordsFree Energy Central Atom Instability Temperature Thermal Softening Atomic Vibration
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