  A global search for possible LiF cluster structures is performed, up to
(LiF)8. The method is based on simulated annealing, where all the energies are
evaluated on the ab initio level. In addition, the threshold algorithm is
employed to determine the energy barriers for the transitions among these
structures, for the cluster (LiF)4, again on the ab initio level; and the
corresponding tree graph is obtained.
