With CBS(T,Q) established as a reasonable methodology for estimating HF/CBS limits of these neutral atoms, Table IV compares this CBS(T,Q) approach with the simpler QZ+CABS for the 5p atoms In-Xe, where it can be seen that CBS(T,Q) always produces a slightly lower energy with a mean deviation between the two estimates of -9 µE h . The Table also shows the convergence of the HF energy with respect to basis set cardinal number, where it can be seen that for In and Sn the improvement in the HF energy is roughly linear, presumably due to changes in energy between successive basis set cardinal numbers being small even at the DZ to TZ level. This suggests that the CBS estimates for these two elements may be slightly too conservative. For the other elements considered, the energy appears to rapidly converging towards a limiting value, with a relative large change from DZ to TZ, and a small change from TZ to QZ. Comparing the QZ+CABS data in Table with that for aVQZ-F12 indicates that the CABS singles correction is very small, clearly less than 1 µE h for In, Sn, Sb, and Xe. As the CABS correction is small, and there is little deviation between CBS(T,Q) and QZ+CABS, CBS(T,Q) is used for estimating HF CBS limits herein.