Atomic and molecular hydrogen interacting with Pt„111..

This computational study is motivated by the apparent conflict between an experiment on dissociation of H2 and D2 on Pt~111!, which suggests a rather corrugated potential energy surface ~PES! for the H2/Pt~111! system, and an experiment showing only weak nonzero-order diffraction of HD scattering from Pt~111!. In the calculations we have used density functional theory ~DFT! within the generalized gradient approximation ~GGA!, including scalar relativistic effects and modelling the Pt~111! surface as a slab. We have found that the H2/Pt~111! PES is both energetically and geometrically corrugated. We have also found that there are reaction paths without or with very low barriers leading to dissociation of H2 on the Pt~111! surface, but that there are other reaction paths with substantial barriers. By performing extensive calculations on H interacting with a Pt~111! surface we have shown that a DFT/GGA approach that includes scalar relativistic effects is capable of describing the interaction between a hydrogen atom and a Pt~111! surface in a way that is, for the most part, consistent with experiments. © 1999 American Institute of Physics. @S0021-9606~99!70648-3#