Density functional studies of the adsorption of OCN and coadsorption of O and CN on Ag(001) surface

The adsorptions of isocyanate (OCN) species, atomic oxygen (O) and molecular fragment (CN) on the Ag(001) surface are studied with four coverages of 0.25, 0.5, 0.75 and 1.0 ML, using density functional theory calculations. The OCN species and atomic oxygen (O) prefer to adsorb at the hollow site for all the coverages. However, two tendencies were observed for the molecular fragment (CN): on the one hand, CN at the bridge site is the most stable at low (0.25) and complete (1.0 ML) coverages; on the other hand, the hollow site becomes the favored site at intermediate (0.5 and 0.75 ML) coverages. The best possible coadsorption configurations for CN and atomic oxygen were investigated. It was found that the coadsorption energy is better when the two fragments were co-adsorbed. The interaction between adsorbate and Ag(001) was analyzed in terms of LDOSs. Finally, the thermochemistry for dissociation of OCN has been discussed.