Fragmentation of small sodium clusters

Fragmentation of small sodium clusters was studied by performing both ab in itio and classical molecular dynamics simulations. In ab initio calculation s at 1200-2400 K, neutral sodium clusters with 10 and 13 atoms ejected both monomers and dimers. The observed behavior is in agreement with previous c alculations stating that the electronic shell oscillations diminish strongl y as a function of temperature. The fragmentation rates obtained with the a b initio method are consistent with the Kelvin equation for the equilibrium vapor pressure of small clusters. The differences between the results obta ined using different models reflect the differences between the dissociatio n energies calculated correspondingly. (C) 2000 American Institute of Physi cs. [S0021-9606(00)31334-4].