THEORETICAL-STUDY OF (NACL)(N) CLUSTERS

In this paper we present the theoretical results obtained for (NaCl)(n ) clusters with n less than or equal to 19, using the ab initio pertur bed-ion (PI) model. That model was first developed for the study of io nic crystals and it has been adapted here to study clusters. Within th e PI model we can determine the total energy of the cluster as a funct ion of the position of the atoms in the cluster and minimizing the tot al energy with respect to those positions we can obtain the ground sta te geometry and other related properties. The results for the equilibr ium geometries are compared with calculations using pair potentials an d with other ab initio results. The study of the relative stabilities of clusters with different numbers of molecules shows that the cluster s are especially stable for n = 4, 6, 9, 12, 15, 16 and 18 molecules, in good agreement with experimental results. We also study some electr onic properties, as for instance ionization potentials.