The second reduction to form the hydroperoxo species can potentially be derived from ascorbate by longrange intramolecular electron transfer to the active site as has been proposed to occur via LPMO aromatic residues localized near the copper active site. An accurate calculated energy difference between the two states will require a multi-determinant QM treatment due to propensity of copper centers to exhibit multiple near degenerate electronic states. This will be addressed in planned future calculations using QM/MM with a multi-determinant wavefunction QM method.