Some difficulties in computing BSSE-corrected potential surfaces of chemical reactions

We performed a theoretical and numerical analysis of the different `counterpoise correctionʹ (CP) schemes potentially applicable to correct for the basis set superposition error (BSSE) in the neighborhood of transition structures of chemical reactions. The analysis proved that neither of them is satisfactory: all CP versions result in either discontinuous potential surfaces or yield different energies for the same species in different reactions. Standard CP correction is unavoidable and satisfactory when loosely bound pre- or post-reaction complexes are studied. For transition structures, however, doing no correction is better than any available CP method.