Temperature and energy partition in fragmentation

We study fragmentation of small atomistic clusters via molecular dynamics. We calculate the time scales related to fragment formation and emission. We also show that some degree of thermalization is achieved during the expans ion process, which allows the determination of local temperature. In this w ay we can calculate the breakup temperature as a function of excitation ene rgy, i.e., the fragmentation caloric curve. Fragmentation appears as a rath er constant temperature region of the caloric curve. Furthermore, we show t hat different definitions of temperature, related to different degrees of f reedom, yield very similar values. [S0556-2813(99)00201-0].