For the Cu(II) and Cu(II)-Cell structures, the spin density (Figure ) shows that for both substrate-bound and unbound states, the spin density is mostly localized on copper. The spin density closely mimics the dx2-y2-orbital, showing that it is reasonable to interpret this orbital as the single-occupied molecular orbital (SOMO), as done by Courtade et al. However, the increase in relative energy of the dx2-y2-orbital cannot be unequivocally confirmed. This may be due to large differences between the LsAA9A LPMO we study here and the AA10 LPMO studied by Courtade et al. or it is a consequence of the different methods employed to model the substrate (Courtade et al. did not include the substrate explicitly in their calculations but used a four-coordinate species to mimic a substrate-bound intermediate).