•Jan Heurich¹, Fabian Pauly¹, Juan Carlos Cuevas¹, Wolfgang Wenzel² und Gerd Schön^1,2
1Institut für theoret. Festkörperphysik, Universität Karlsruhe
²Institut für Nanotechnologie, Forschungszentrum Karlsruhe

We present a theory for the electrical conductance of a single hydrogen molecule between Pt leads explaining recent experimental obervations by Smit et. al. (Nature 419, 906-909, (2002)). We develop a simple theoretical model to understand the conduction mechanism through the hydrogen bridge and match it to quantitative density functional calculations. Our analysis elucidates which specific ingredients are required for the proper description of the system. In particular we identify how symmetry induced interference effects, similar to those known from light propagation in photonic crystals and sound propagation in periodic structures, control the number of available conduction channels. We also show how the analysis of the conduction channels gives information about the experimentally realized contact geometry.