CLUSTER THEORY OF ATOMIC AND MOLECULAR CHEMISORPTIONS ON NI AND CU

Atomic (O, S, Se) and molecular (NO, O2) chemisorptions on Ni and Cu are studied using the discrete variational Xα cluster method. The calculated cluster levels are in good agreement with experimental UPS peaks for corresponding chemisorption systems. The atomic and molecular chemisorptions are described in a similar way by the electron donation and the backdonation. The adsorbate level positions relative to the metal band are very important in chemisorption mechanism. For atomic chemisorptions, the net charge on adatom and the covalency between adatom and metal gradually increase on going from O to Se. For molecular chemisorptions, the σ-donation is predominant and the adsorbates become positive contrary to the case of CO chemisorptions. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.