We next address the performance of the STM and GSTM approaches, which are quite different (for a given functional) as compared to the ∆SCF results. The Slater-type methods are orbital-based estimates of CEBEs, rather than many-electron descriptions, and they depend on the accuracy of the Kohn-Sham oneparticle energy levels. Both delocalization error (whose magnitude may be inferred by the performance of semilocal functionals) and localization error (as inferred by the performance of HF calculations) become critically important.