The energetics of adsorption of HCOOH on the MgO(100) surface

Abstract

Ab initio calculations based on density functional theory and the pseudopotential method have been used to investigate the adsorption of HCOOH (formic acid) on the flat non-defective MgO(100) surface. The aims of the work are to find the energetically most favorable adsorbed configurations, and to determine whether dissociative adsorption is favorable. The calculations are performed in slab geometry using periodic boundary conditions. They are fully converged with respect to the size of the plane-wave basis set, and full relaxation of all atoms in the system is performed throughout. Results obtained both with the local density approximation and including generalized gradient corrections are presented. It is found that the most stable configuration is dissociative, with the formate ion symmetrically attached via its oxygen atoms to two surface Mg ions. This configuration is more stable than the most stable molecular configuration by ∼0.3 eV. The energy barrier separating molecular and dissociated adsorbed configurations is small, so that spontaneous dissociation would occur under all conditions of interest. The relations between our findings and previous experimental and theoretical results are discussed.