Charge-induced fragmentation of sodium clusters

The fission of highly charged sodium clusters with fissilities X > 1 is studied by ab initio molecular dynamics. Na-24(4+) is found to undergo predominantly sequential Na-3(+) emission on a time scale of 1 ps, while Na-24(Q+) (5 less than or equal to Q less than or equal to 8) undergoes multifragmentation on a time scale greater than or equal to0.1 ps, with Na+ increasingly the dominant fragment as Q increases. All singly charged fragments Na-n(+) up to size n = 6 are observed. The observed fragment spectrum is, within statistical error, independent of the temperature T of the parent cluster for T less than or equal to 1500 K. These findings are consistent with and explain recent trends observed experimentally.