Abstract
The interactions of CO and of C+O with Fe-13 have been studied by the PW91, PW91+U, B3LYP density functional theory-based methods. In each case, various possibilities have been explored for N-alpha-N-beta. All methods predict an icosahedral structure for the naked particle. Moreover, all density functionals predict CO adsorption on threefold hollow site. Depending on the density functional used, the interaction of CO with the Fe13 cluster induces or not a change in the total number of unpaired electrons and, therefore, of the electronic state. The same situation can appear for the dissociation of adsorbed CO to co-adsorbed C+O. In the most stable configuration, C and O are proximate, bound to a common Fe atom that is oxidized. These results suggest the proper description of the reactivity of magnetic metallic nanoparticles toward dissociation of simple diatomic molecules is likely to involve various spin states, which has implications for the search of the corresponding transition states which cannot be restricted to a single potential energy surface.