Step energies and step–step interactions on vicinal surfaces of Rh and Pd

The calculation of step energies and a fortiori of step–step interactions in transition metals remains up to now out of reach of ab initio methods. Using a tight-binding model in a s, p and d orbital basis set we have studied the energetics of several vicinal surfaces of Rh and Pd with (1 1 1), (1 0 0) and (1 1 0) terrace orientations. The energy per step atom exhibits a damped oscillatory behaviour as a function of the terrace width. This reveals the existence of oscillatory electronic step–step interactions that are strongly dependent on the geometry and on the element and are of the same order of magnitude as other interactions. The possible existence of a magnetic moment in the vicinity of the step edges is also discussed.