  Unimolecular evaporation in rotating atomic clusters is investigated using
phase space theory (PST) and molecular dynamics simulations. The rotational
densities of states are calculated in the sphere+atom approximation, and
analytical expressions are given for a radial interaction potential with the
form -C/r^p. The vibrational densities of states are calculated using Monte
Carlo simulations, and the average radial potential at finite temperature is
obtained using a recent extension of the multiple range random-walk algorithm.
These ideas are tested on simple argon clusters modelled with the Lennard-Jones
(LJ) interaction potential, at several total energies and angular momenta of
the parent cluster. Our results show that PST successfully reproduces the
simulation data, not only the average KER but its probability distribution, for
dissociations from LJ_14, for which the product cluster can effectively be
considered as spherical. Even for dissociations from the nonspherical LJ_8,
simulation results remain very close to the predictions of the statistical
theory.
