Adsorption geometry of benzene on Pd(110): Results of first-principles calculations

The atomic structure of the Pd(110)-c(4 x 2)-benzene system has been determined by means of ab initio slab calculations. A C-2 low-symmetry equilibrium configuration is predicted. The corresponding azimuthal angle theta similar to 11 degrees of the adsorbed molecule is partly due to lateral interactions. The aromatic ring looses planar geometry and the C-H, bonds bend away from the metal. STM images calculated for the C-2 configuration are compatible with recent experimental data.