Hence, the linear relation between charge transfer and Ru-induced lowering of the O-vacancy formation energy, which was derived for the formation of individual O vacancies, is also applicable to O-vacancy formation in a cluster. For the VO(5i) vacancy, where the O-vacancy formation energy and the Ru-induced lowering of it are significantly lower than expected from the linear regression, the structural contribution ( ∆𝐸 𝑅𝑢 𝑑𝑒𝑓𝑜𝑟𝑚 + ∆𝐸 𝑠𝑢𝑝𝑝𝑜𝑟𝑡 𝑑𝑒𝑓𝑜𝑟𝑚 ) (Table ) is significantly higher than for the VO(2i) and VO(4i) O-vacancies, supporting the role of restructuring effects as discussed before. On the other hand, these deviations (Figure and) are much smaller for the VO(3i) site, supporting our above suggestion that larger structural contributions are an important, but not the only possible origin for a significant deviation from the linear relation between charge transfer and Ru-induced stabilization of an O-vacancy. ). We disregarded the 10i -12i sites, since they are located underneath the interface perimeter, similar to the 1i -3i oxygen atoms. From these sites, 16i -18i and in particular 16i and 17i are closer to the edge of the Ru nanorod and therefore termed as first row sites, while sites 13i -15i are further apart (second row). O-vacancy formation energies obtained for the bare ZrO2 system and on the Ru/ZrO2 model system are plotted in Figure (see also Tables and Possible correlations between the charge transfer from the support to the Ru nanorod and the O-vacancy formation energy or the Ru-induced lowering of that quantity are illustrated in Figure and 5c, respectively (see also Table ). Also for these sites there is still some charge