Focusing momentarily on the convergence of ∆d with respect to basis set size, it can be seen in Table VII that convergence appears to be rapid, with the TZ results close to those from QZ. As expected, there is a larger, although still relatively small, difference between ∆d at the DZ level and the same quantity evaluated with the TZ basis. In some cases, namely with a mean absolute deviation of 0.06 kcal mol -1 and a maximum deviation of 0.12 kcal mol -1 . The ∆CV values are based on extrapolations to the CCSD(T)/CBS limit using aug-cc-pwCVnZ-PP (n = Q, 5) basis sets with all electrons not replaced by the PP correlated, hence these also correlate the (m -1)sp electrons along with (m -1)d. Overall, the rapid convergence of ∆d, and the excellent agreement with ∆CV, reinforces the finding that F12 methods with the (aug-)cc-pVnZ-PP-F12 family of basis sets are an efficient way of recovering this important correlation effect.