We performed a systematic investigation of the small BxNy
(x+yβ€6) clusters using the ab initio Hartree-Fock scheme plus
second-order perturbation theory. The nature of the potential energy
surface extrema are analyzed through analytical total energy second
derivatives. Ionization potentials, binding energies and the stability
against some possible reaction mechanisms are calculated. Based on these
results we propose that the growing process for these clusters is mainly
due to the successive incorporation of BN molecules. A discussion of some
mass spectrometry experimental results is also presented