The model of the stepped Au(533) surface employed in the calculations: (a) side view of the slab with each unit cell shown in a different color; (b) top view of stepped surface. Each unit cell contains four (111) layers and is offset to create a step. Yellow circles are the gold atoms that make up the upper step, orange circles represent the terrace, and purple circles are the layer of the lower step. White circles represent initial starting positions and solid green circles the final positions of the chlorine atom after relaxation. The vector normal to the plane of the step edge, , is shown in (a) and the lattice unit cell vectors and are shown in (b).
Chlorine adsorption sites on the Au(111) surface with a Au adatom. Orange circles represent the top layer of the gold, the yellow circle is the gold adatom, and smaller numbered green circles indicate the relaxed chlorine positions.
Adsorption energy of atomic chlorine as a function of number of vacancies on Au(111). Orange circles represent the top layer of gold and purple circles the second layer of gold. With only one vacancy there are three different configurations we considered: the gold atom removed to create the vacancy and the corresponding energy value are labeled A, B, and C. The optimal structure (with highest absorption energy) corresponds to three gold vacancies and the chlorine atom at the threefold site on top of the remaining top-layer gold atoms, shown in the middle configuration. The structure with the highest number of vacancies (13) and its energy are shown on the right.
Charge difference plots for (a), (b) chlorine bound next to a gold vacancy and (c) chlorine bound on top of a gold adatom. Structural figures on the side of each plot indicate the atomic arrangements; the black line in each case indicates the plane on which the charge difference is plotted. Each plot corresponds to an area of .
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