In the above equations ∆E CBS MP2-F12 is the MP2-F12 correlation energy extrapolated to the CBS limit using the n -3 formula 41 and ∆E CV MP2-F12 is the MP2-F12 energy difference between all electron (ae) and frozen core (fc) calculations employing the cc-pwCVTZ basis set (C3Z). At this level, the extrapolation of Hartree-Fock (HF) and correlation contributions is performed with the same equation and basis sets since several tests have shown that this simplified recipe has a negligible impact on the overall accuracy of the results. Derivation of Equation 2 w.r.t. Cartesian coordinates leads to the junChS-F12 version of the so called "gradient scheme" introduced by Gauss and coworkers for geometry optimizations by composite methods