Having suggested that spin-delocalized DFT hemibonds play an important role in rationalizing the experimental UV spectrum, what does this new observation of spin-localization at the MP2 level say about the UV spectroscopy of OH(aq)? To answer this question, we turn to hemibonded dimer and pentamer cluster models for which we have computed absorption spectra by varying the distance between the hydroxyl moiety and the neighboring water molecules, leaving the exposed O * • • • O facet in place. The evolution of various properties as a function of r O * O is shown in Tables and. The spin charge rapidly localizes onto the radical as the O * • • • O distance increases, yet the most intense feature in the electronic spectrum remains a charge-transfer transition from the water molecule that is pseudo-hemibonded to the radical, even for r O * O = 3.4 Å where spin localization is complete. The presence of several additional water molecules in the case of OH(H 2 O) 4 does not alter this observation.