Microsolvation of Li+ in bosonic helium clusters. I. Many-body effects on the structures of the small aggregates

Ab initio post-Hartree-Fock calculations are performed for the potential energy curve of the LiHe+ diatomic system and for the optimal structures of Li(He)n+ clusters, with n from 1 to 6. MP4 optimizations with the cc-pVQZ basis set have been carried out and the results compared with the structures obtained by energy optimization procedure using pairwise potentials. The results are shown to remain very close to those obtained by including many-body effects in the full geometry optimization.