Effect of the exchange-correlation potential and of surface relaxation on the description of the H2O dissociation on Cu(111)

The role of the exchange-correlation density functional (PBE, PW91, RevPBE) and of surface relaxation in the determination of the adsorption energies, reaction energy barriers, and reaction rate constants has been analyzed taking water dissociation on Cu(111) surface as a test case. The PBE and PW91 functionals yield similar adsorption geometries and, adsorption and activation energies, but differ significantly from RevPBE results. For each of the functionals tested, surface relaxation was found to have only a minor effect on the calculated (co)adsorption geometries and (co)adsorption energies. The calculated energy barriers for water dissociation are more affected by the functional used, especially in the case of the RevPBE, with obvious implications on the calculated energy barriers and derived reaction rate constants. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3149851]