Moving on to the 2VO system, we find a pronounced increase of the charge on the Ru-3a surface atom (Table ), which leads to a change in the adsorption site to the (Ru-2a, Ru-3a, Ru-6a) threefold hollow site. Hence, for the 2VO system, adsorption on this site is more stable than on the Ru-2a / Ru-6a bridge site, while for the 0VO and 1VO systems it was opposite. This goes along with a pronounced increase in CO adsorption energy on the 2VO system (Figure ).