engleski

Solution of the CO puzzle problem

Adsorption of the CO molecule on (111) metal surfaces is the benchmark system for experimental and theoretical methods. For the last 20 years the standard theory for the calculation of chemisorption, adsorption, chemical reactions and electronic structure in general is the Density Functional Theory (DFT). Despite the great successes of the theory in predicting adsorption energies and other properties for many systems it turns out that the theory fails to predict correctly the adsorption site preference for the CO molecule on (111) surfaces of Pt, Cu and Rh for example. The theory predicts that the FCC (hollow) i.e. the highly coordinated site adsorption is preferred over the TOP site adsorption while experiments show unambiguously that CO adsorbs in TOP site. Also the calculated adsorption energies do not match well the experimental values. CO molecule chemisorption on these surfaces is a type of system in which one expects DFT theory and its present implementation with semi-local energy functionals to work well. Systems for which DFT is not good due to its semi-locality of the energy functional are those in which part of the sysfem is physisorbed and physisorption dominates over chemical bonding, i.e. typical van der Waals systems. However van der Waals is specific name for a more general phenomenon called nonlocal correlation. We show the nonlocal correlation is crucial to solve the CO puzzle problem.

CO; transition metals; (111) surface; DFT; van der Waals interaction

nije evidentirano