Fragmentation Phase Transition in Atomic Clusters II -----Symmetry of Fission of Metal Clusters----

摘要

We present a statistical fragmentation study of doubly charged alkali (Li,Na, K) and antimony clusters. The evaporation of one charged trimer is the mostdominant decay channel (asymmetric fission) at low excitation energies. Forsmall sodium clusters this was quite early found in molecular dynamicalcalculations by Landman et al. For doubly charged lithium clusters, we predictLi$_{9}^{+}$ to be the preferential dissociation channel. As already seenexperimentally a more symmetric fission is found for doubly charged antimonyclusters. This different behavior compared to the alkali metal clusters is inour model essentially due to a larger fissility of antimony. This is checked byrepeating the calculations for Na$_{52}^{++}$ with a bulk fissility parameterset artificially equal to the value of Sb.