Similar plots of the center of the d-band density of states vs. the charge on the Ru adsorption sites (Figure ) lead to almost identical results, with a linear correlation between these parameters. Hence, a more negatively polarized Ru adsorption site results in an upshift of the d-band center. Interestingly, in this case the difference in slopes between interface (i) and interface (ii) sites is much less than for in the plots of the adsorption energy adsorption (Figure ). In combination, this reflects the experience that the energy of the center of the d-band LDOS affects the CO adsorption energy to different extents, depending on the nature of the material and the exact adsorption site. The few systems which deviate from this linear correlation are partly the same as in Figures , namely the 5VO system for both interface sites, and the 1VO(7i) system for adsorption on the interface (ii) site. All of these cases involve a change in adsorption site, which affects the calculation of the charge and of the d-band center on the adsorption site by addition/removal of specific Ru atoms. Hence, most simply, these deviations are due to limitations in the simple averaging procedure of these values for adsorption sites with several surface atoms contributing.