Orbital basis sets specifically optimized for use in F12 calculations display a smoother convergence towards the CBS limit (when used in F12 calculations) than conventionallyoptimized basis sets. For full details of the development of correlation consistent basis sets for use in F12 calculations, which are often abbreviated to VnZ-F12, the interested reader is referred to Ref. , but as a high-level outline they are typically optimized at the MP2-F12 level of theory and aim to balance the basis set incompleteness errors in both the Hartree-Fock and correlated components of the total energy. To address the latter point, a given VnZ-F12 orbital basis includes, for elements from the second and third periods, the (HF-like) s and p functions from the aug-cc-pV(n+1)Z basis. The exponents of the optimized correlating functions with the orbital basis are also usually more diffuse than those from an equivalent correlation consistent basis for use in conventional correlated calculations.