Dhe. Gross et Pa. Hervieux, STATISTICAL FRAGMENTATION OF HOT ATOMIC METAL-CLUSTERS, Zeitschrift fur Physik. D, Atoms, molecules and clusters, 35(1), 1995, pp. 27-42
Fragmentation processes of highly excited neutral and charged atomic m
etal clusters are studied in the framework of an equilibrium statistic
al model. In the particular case of hot (near and above melting) neutr
al and charged sodium clusters of 100 and 200 atoms, a microcanonical
Metropolis sampling is used to compute mass (or charge) correlation fu
nctions as a function of the excitation energy. This method allows to
take the strong anharmonicities in the internal phonon spectrum realis
tically into account which are linked to the internal structural chang
es like melting. It is found that, at high enough excitation energy, t
he system exhibits a phase transition. This phase transition is specif
ic for fragmenting finite systems. From the shape of the caloric curve
one sees that the two phases involved are connected by a van der Waal
s loop characterizing a first order phase transition. Here we observe
an enhanced fission and multifragmentation into two or more charged cl
usters with more than 10 atoms each. Various fragment correlations are
studied.