Energetics of steps on Pt(111)

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Abstract
First-principles local-density approximation optimizations for Pt(331), Pt(221), Pt(211), and Pt(533) slabs, the surfaces of which are vicinal to Pt(111), are used to extract approximate theoretical energies per unit length for the two varieties of unkinked step on Pt(111). As expected on the basis of bond counting, the calculated energies of the (111)-type and (100)-type steps are nearly equal, about 0.46–0.47 eV per step-edge atom. Near equality of the step-formation energies does not agree with Michely and Comsa’s finding that (111)-type edges are about 50% longer than (100) edges for islands on Pt(111) equilibrated at 700 K, corresponding to a formation free energy that is 13% lower.