Having demonstrated the ability to refine a MOF structure using fragment-based HAR, we next turned to testing the effect of the quantum mechanical method (QM) used to calculate the electronic structure on the resulting structure geometry, namely the length of C-H bonds and the hydrogen ADPs. The calculations were performed with the Hartree-Fock (HF) method, as well as PBE 10 and B3LYP 24 DFT functionals. For each of these QMs we used two different split-valence Pople basis sets (6-31G and 6-311G), and two correlationconsistent polarized valence-only basis sets (cc-pVDZ and cc-pVTZ). The results of the comparisons are summarized in Table , where the PBE method with cc-pVTZ was chosen as a reference for comparison with all the other methods. Overall, the selection of basis set has a greater impact on all the structural parameters, and particularly C-H bond lengths, than the QM method choice.