Adsorption of single Cu atoms at differently stabilized polar ZnO surfaces: An ab initio study.

In this study, the adsorption of a single Cu atom on the polar ZnO(0001) and ZnO(0001) surfaces was investigated by means of highly accurate wave function based ab initio methods. Different modifications of the polar surfaces were investigated: unstabilized surfaces, surfaces with hydrogen and OH overlayers, and defectious surfaces. Cu is strongly bound at the unstabilized surfaces by a charge transfer mechanism which induces a stabilization of the surface.

Understanding the infrared spectrum of bare CH5+.

Protonated methane, CH5+, continues to elude definitive structural assignment, as large-amplitude vibrations and hydrogen scrambling challenge both theory and experiment. Here, the infrared spectrum of bare CH5+ is presented, as detected by reaction with carbon dioxide gas after resonant excitation by the free electron laser at the FELIX facility in the Netherlands. Comparison of the experimental spectrum at approximately 110 kelvin to finite-temperature infrared spectra, calculated by ab initio molecular dynamics, supports fluxionality of bare CH5+ under experimental conditions and provides a dynamical mechanism for exchange of hydrogens between CH3 tripod positions and the three-center bonded H2 moiety, which eventually leads to full hydrogen scrambling.