Energetics and dynamics for NO and CO dissociation on Cu(100) and Cu(111)

The dissocn. of NO and CO has been studied on cluster models representing the copper (100) and -(111) single-crystal faces using d. functional quantum calcns. For each surface, several possible reaction paths are proposed, for which we fully optimized the reactant, product, and transition states at the local d. level (LDA). Nonlocal d. functional calcns. (NLDA) were then performed on these optimized geometries. The clusters we used, varying in size between 13 and 31 atoms, produced dissocn. barriers and energies that were reasonably well converged with cluster size. Classical transition-state theory was used to calc. the rates of dissocn. and recombination on the basis of computed frequencies of the predicted transition state and the reactant and product states. The transition states for NO and CO dissocn. on all surfaces can be described as \"tight\" transition states corresponding to preexponentials for dissocn. in the range 1010-1013 s-1. The dissocn. barrier for NO is significantly lower than that for CO. In addn., the more open Cu(100) surface is more reactive toward dissocn. than the close-packed Cu(111) surface. Nonlocal corrections to the LDA functional were found to have a small effect on dissocn. barrier height, but the effect was found to be more profound on the recombination barrier and overall dissocn. energies