Top view of a (1 × 1) unit cell of Pt(211). Indicated is the irreducible wedge by a blue plane and the blue dots represent the positions of H and of the center of mass of H2, respectively, at which DFT energy points were calculated in order to construct the 3D/6D PES. A few selected sites are labeled with top, brg (bridge) and t2b (top to bridge) and are further distinguished by numbers. Red dots indicate periodic images at the edge of the irreducible wedge.