Fragmentation of Sn clusters studied by time-dependent Hartree-Fock calculations

Fragmentation of tin clusters of size N less than or equal to 50 has been studied using time-dependent Hartree-Fock calculations. The calculations are based on a mixed scheme where the nuclear variables are treated classically using Pulay forces and the electronic configuration is obtained by the minimization of the total energy. The evaluation of the Hamiltonian is performed using either the ab initio formulation or the Modified Neglect of the Differential Overlap(MNDO) approximation. Fragmentation is obtained by increasing the kinetic energy E-k of the nuclear subsystem and starts from the stationary state of minimal energy. The objective of this study is twofold. On one side, the merits and shortcomings of MNDO are illustrated by the comparison with ab initio calculations and literature data. On other side, in order to get insight into the physics of fragmentation, the effects of E-k and N are analyzed and discussed.