Total Structural Energy of Top-Site-Adsorbed CO/Ni_x--Cu_1-x Systems

We construct an atomic group model of the disordered binary alloy Ni_x--Cu_1-x for the cases that the surface composition segregation exists or not. According the model, we calculate the electronic structure in a top site of Ni_x--Cu_1-x alloy surface by using the recursion method when CO absorbed on the Ni_x--Cu_1-x surface under the condition of coverage 0.5. The calculation result indicates that chemical absorption of CO reduces the density of states of the disordered binary alloy Ni_x--Cu_1-x, widens the energy band, and strengthens the covalent bonds between the d electron of Ni and s or p electron of CO. Chemisorption of CO inhibits the enrichment of atom Cu on the alloy surface especially when bulk Ni concentration x is less than 0.8.