) than obtained for the O-vacancies on 4i and 7i sites, which are further away from the adsorption site (Figure and Table ). This, however, is compensated by a slightly higher positive contribution from the deformation energies, leaving the total CO adsorption energy essentially constant. For adsorption on the interface (ii) site (Figure and Table ), the difference between CO binding energy and CO adsorption energy, which is given by the sum of the COad induced deformation energy and difference in interface energies, is generally bigger than for adsorption on the interface (i) site. Apparently, these latter contributions are mainly responsible for the lower adsorption energies on the interface (ii) site. This is particularly true for adsorption on this site in the 1VO(7i) system