This also allowed us to separate changes in the vacancy formation energy caused by the different location of the O-vacancy from those introduced by the presence of neighboring Ovacancies, in a growing O-vacancy island, which was not possible in earlier calculations. The driving force for the formation of O-vacancy islands was calculated by consecutive removal of neighboring O-atoms in the lattice, both in the presence and in the absence of the Ru nanorod. Furthermore, we now included not only surface vacancy islands underneath the Ru nanorod (removal of O-atoms from 1i to 5i in Figure ), but also surface O-vacancy islands aside the Ru nanorod, formed by sequential removal of O-atoms 1i, 17i, 18i, and 14i, and finally vertical O-vacancy islands underneath the edge of the Ru nanorod created by consecutive removal of O atoms 1i, ii, iii and iv.