Accurate and efficient determination of chemisorption energies using pseudopotentials

The accuracy and efficiency of ab initio density functional theory calculat ions depend critically on the choice of pseudopotenlial. In this study, the merits of using large-core pseudopotentials for the dissociative chemisorp tion of oxygen on rhodium are discussed. The results show that these effici ent pseudopotentials yield adsorption energies and bond distances of the ox ygen atom to rhodium that are in close agreement with calculations performe d with small core pseudopotentials. However, to compute the dissociative ch emisorption energy, a small-core calculation of the free O-2 molecule must also be performed to ensure accurate results. The use of pseudopotentials w ith different core radii for different aspects of the calculation leads to enhanced efficiency. (C) 1999 Elsevier Science B.V. All rights reserved.