CLASSICAL PATH SURFACE-HOPPING DYNAMICS .2. APPLICATION TO AR3+

A classical path surface-hopping trajectory approach is applied to the study of the dissociation of singly charged argon trimer-ions produced in the ionization process Ar3 --> Ar3+ --> Ar2+ + Ar. Production of the ions in each of the first three adiabatic states is investigated with a view to describing the dynamics of the newly produced ion from its formation up to the time it dissociates. In the ground state, the motion typically involves several sequences of a vibration of the charged pair in a dimer subsystem Ar2+, followed by charge transfer to form a different dimer subsystem. In the second and third states, there is concerted motion until passage of a nonadiabatic region leads to a transition to the ground state, from whence dissociation occurs via a sequence of pair collisions. In the third state, the motion is more erratic, the charge being delocalized a large fraction of the time. The different dynamical mechanisms are interpreted in terms of charge migration and nonadiabatic effects. A few trajectories for Ar(n)+ for n = 3, 4, and 5 exhibit similar charge migration behavior, suggesting the applicability of these dissociation mechanisms to small clusters.