This 65 Pd-atom model is oriented as follows. Perpendicular to the graphene sheet: (111)Pd is parallel to (00.2)graphene, while in the plane of the graphene sheet: [112]Pd is parallel to [01.0]graphene. This is in agreement with diffraction data reported on fcc-metal/graphite epitaxy in the literature. In addition, two of every three Pd atoms are positioned directly over a carbon atom, while one of every three is over the center of a cyclohex ring. We think that this translational choice is the only one that doesn't exhibit a symmetry-breaking displacement with respect to the graphene lattice, although we have no reason to think that it's the lowest energy alternative. Epitaxy of this sort on carbon nanotube surfaces may be one of the better places to see how well this model agrees with experiment.
Below find some Pd nanoparticles on a multiwall carbon nanotube.
Below are predicted (111) fringe orientations visible depending on tube chirality and the nature of the interface between carbon and metal.
Here's a closer look at the graphene plane itself:
