The method we proposed recently [J. Chem. Phys., 114, 1447 (2000)] to a posteriori correct the unphysical dissociation behavior of radical homonuclear diatomic cations obtained in density functional theory calculations has been enlarged to nonsymmetric three-center two electrons systems. This approach, which is derived from Slater's transition state technique, allows to remove most of the self-interaction energy error contained in the current exchange functionals. It has been shown that this is the main contribution to the overestimation of the bonding energy of systems with delocalized charges. Although approximate, the method yields a better agreement with experimental bonding energies than more sophisticated methods.