Fig. 6
Diffusion paths of atomic H on Au18. Red arrows indicate the spatially shortest diffusion path between the two most stable b3 sites, which has an overall barrier of 0.52 eV with respect to the global minimum. Green arrows indicate the most energetically favorable diffusion path, which has an overall barrier of 0.41 eV with respect to the global minimum. Blue and black spheres represent stable H adsorption sites on the green and red diffusion paths, respectively; gold spheres represent Au atoms. Side view 2 is rotated by 90° with respect to side view 1. Dotted pink triangles mark the two triangular ensembles of Au atoms in Au18, identical to those in Fig. 2
