The effect of strain on the adsorption of CO on Pd(100)

We study how the binding energy, the vibrational frequencies and the adsorp tion isotherm of CO on Pd(100) are modified when the solid is subject to un iform strain. The parameters controlling the thermodynamics of adsorption ( the adsorption energy, the vibrational frequencies of the adsorbed molecule s and the interaction energy between the molecules) have been calculated by using density functional theory. These parameters are then used in a grand canonical Monte Carlo simulation that determines the CO coverage when the surface is in thermodynamic equilibrium with a CO gas, at a specified press ure and temperature. We find that this is substantially affected by the str ain. Our results, along with those obtained by others, suggest that the dev elopment of "elastochemistry," a study of the change in the chemical proper ties of a surface when subjected to strain will lead to interesting and mea surable results. It also suggests that differences in chemical activity bet ween clusters on a support and clusters in gas phase may be partly due to t he strain induced when a cluster is placed on the support. (C) 2000 America n Institute of Physics. [S0021-9606(00)00627-9].