Minimal interatomic distance in Morse clusters

In this paper we derive a lower bound, independent from the number of atoms N , for the minimal interatomic distances between atoms in a cluster whose total energy is modelled by means of the so called Morse potential. A similar result was previously proven for Lennard-Jones clusters but the proof can not be extended to Morse clusters. Besides the theoretical interest, the derivation of this lower bound is important for the definition of efficient procedures for the computation of the total energy of clusters with a large number of atoms.